Input File Description

a string describing the task to be performed:
   'cp',
   'scf',
   'nscf',
   'relax',
   'vc-relax',
   'vc-cp',
   'cp-wf',
   'vc-cp-wf'

   (vc = variable-cell).
   (wf = Wannier functions).
         

reprinted on output.
         

In order of decreasing verbose output:
 'debug' | 'high' | 'medium' | 'low','default' | 'minimal'
         

Number of steps between successive savings of
information needed to restart the run.
         

'from_scratch'   : from scratch
'restart'        : from previous interrupted run
'reset_counters' : continue a previous simulation,
                   performs  "nstep" new steps, resetting
                   the counter and averages
         

number of ionic + electronic steps
         

Number of steps between successive writings of relevant physical quantities
to files named as "prefix.???" depending on "prefix" parameter.
In the standard output relevant quantities are written every 10*iprint steps.
         

Write stress tensor to standard output each "iprint" steps.
It is set to .TRUE. automatically if
calculation='vc-relax'
         

print forces. Set to .TRUE. when ions are moving.
         

time step for molecular dynamics, in Hartree atomic units
(1 a.u.=2.4189 * 10^-17 s : beware, PW code use
 Rydberg atomic units, twice that much!!!)
         

input, temporary, trajectories and output files are found
in this directory.
         

This flag controls the saving of charge density in CP codes:
If  .TRUE.        save charge density to restart dir,
If .FALSE. do not save charge density.
         

prepended to input/output filenames:
  prefix.pos : atomic positions
  prefix.vel : atomic velocities
  prefix.for : atomic forces
  prefix.cel : cell parameters
  prefix.str : stress tensors
  prefix.evp : energies
  prefix.hrs : Hirshfeld effective volumes (ts-vdw)
  prefix.eig : eigen values
  prefix.nos : Nose-Hoover variables
  prefix.spr : spread of Wannier orbitals
  prefix.wfc : center of Wannier orbitals
  prefix.ncg : number of Poisson CG steps (PBE0)
         

Units for input and output restart file.
         

Units for input and output restart file.
         

.true. to compute the volume and/or the surface of an isolated
system for finite pressure/finite surface tension calculations
(PRL 94, 145501 (2005); JCP 124, 074103 (2006)).
         

jobs stops after max_seconds CPU time. Used to prevent
a hard kill from the queuing system.
         

convergence threshold on total energy (a.u) for ionic
minimization: the convergence criterion is satisfied
when the total energy changes less than etot_conv_thr
between two consecutive scf steps.
See also forc_conv_thr - both criteria must be satisfied
         

convergence threshold on forces (a.u) for ionic
minimization: the convergence criterion is satisfied
when all components of all forces are smaller than
forc_conv_thr.
See also etot_conv_thr - both criteria must be satisfied
         

convergence criterion for electron minimization:
convergence is achieved when "ekin < ekin_conv_thr".
See also etot_conv_thr - both criteria must be satisfied.
         

'high': CP code will write Kohn-Sham wfc files and additional
        information in data-file.xml in order to restart
        with a PW calculation or to use postprocessing tools.
        If disk_io is not set to 'high', the data file
        written by CP will not be readable by PW or PostProc.
         

'small': memory-saving tricks are implemented. Currently:
         - the G-vectors are sorted only locally, not globally
         - they are not collected and written to file
         For large systems, the memory and time gain is sizable
         but the resulting data files are not portable - use it
         only if you do not need to re-read the data file
         

directory containing pseudopotential files
         

If .TRUE. a homogeneous finite electric field described
through the modern theory of the polarization is applied.
         

  Bravais-lattice index. If ibrav /= 0, specify EITHER
  [ celldm(1)-celldm(6) ] OR [ A,B,C,cosAB,cosAC,cosBC ]
  but NOT both. The lattice parameter "alat" is set to
  alat = celldm(1) (in a.u.) or alat = A (in Angstrom);
  see below for the other parameters.
  For ibrav=0 specify the lattice vectors in CELL_PARAMETER,
  optionally the lattice parameter alat = celldm(1) (in a.u.)
  or = A (in Angstrom), or else it is taken from CELL_PARAMETERS

ibrav      structure                   celldm(2)-celldm(6)
                                     or: b,c,cosab,cosac,cosbc
  0          free
      crystal axis provided in input: see card CELL_PARAMETERS

  1          cubic P (sc)
      v1 = a(1,0,0),  v2 = a(0,1,0),  v3 = a(0,0,1)

  2          cubic F (fcc)
      v1 = (a/2)(-1,0,1),  v2 = (a/2)(0,1,1), v3 = (a/2)(-1,1,0)

  3          cubic I (bcc)
      v1 = (a/2)(1,1,1),  v2 = (a/2)(-1,1,1),  v3 = (a/2)(-1,-1,1)

  4          Hexagonal and Trigonal P        celldm(3)=c/a
      v1 = a(1,0,0),  v2 = a(-1/2,sqrt(3)/2,0),  v3 = a(0,0,c/a)

  5          Trigonal R, 3fold axis c        celldm(4)=cos(alpha)
      The crystallographic vectors form a three-fold star around
      the z-axis, the primitive cell is a simple rhombohedron:
      v1 = a(tx,-ty,tz),   v2 = a(0,2ty,tz),   v3 = a(-tx,-ty,tz)
      where c=cos(alpha) is the cosine of the angle alpha between
      any pair of crystallographic vectors, tx, ty, tz are:
        tx=sqrt((1-c)/2), ty=sqrt((1-c)/6), tz=sqrt((1+2c)/3)
 -5          Trigonal R, 3fold axis <111>    celldm(4)=cos(alpha)
      The crystallographic vectors form a three-fold star around
      <111>. Defining a' = a/sqrt(3) :
      v1 = a' (u,v,v),   v2 = a' (v,u,v),   v3 = a' (v,v,u)
      where u and v are defined as
        u = tz - 2*sqrt(2)*ty,  v = tz + sqrt(2)*ty
      and tx, ty, tz as for case ibrav=5
      Note: if you prefer x,y,z as axis in the cubic limit,
            set  u = tz + 2*sqrt(2)*ty,  v = tz - sqrt(2)*ty
            See also the note in flib/latgen.f90

  6          Tetragonal P (st)               celldm(3)=c/a
      v1 = a(1,0,0),  v2 = a(0,1,0),  v3 = a(0,0,c/a)

  7          Tetragonal I (bct)              celldm(3)=c/a
      v1=(a/2)(1,-1,c/a),  v2=(a/2)(1,1,c/a),  v3=(a/2)(-1,-1,c/a)

  8          Orthorhombic P                  celldm(2)=b/a
                                             celldm(3)=c/a
      v1 = (a,0,0),  v2 = (0,b,0), v3 = (0,0,c)

  9          Orthorhombic base-centered(bco) celldm(2)=b/a
                                             celldm(3)=c/a
      v1 = (a/2, b/2,0),  v2 = (-a/2,b/2,0),  v3 = (0,0,c)
 -9          as 9, alternate description
      v1 = (a/2,-b/2,0),  v2 = (a/2, b/2,0),  v3 = (0,0,c)

 10          Orthorhombic face-centered      celldm(2)=b/a
                                             celldm(3)=c/a
      v1 = (a/2,0,c/2),  v2 = (a/2,b/2,0),  v3 = (0,b/2,c/2)

 11          Orthorhombic body-centered      celldm(2)=b/a
                                             celldm(3)=c/a
      v1=(a/2,b/2,c/2),  v2=(-a/2,b/2,c/2),  v3=(-a/2,-b/2,c/2)

 12          Monoclinic P, unique axis c     celldm(2)=b/a
                                             celldm(3)=c/a,
                                             celldm(4)=cos(ab)
      v1=(a,0,0), v2=(b*cos(gamma),b*sin(gamma),0),  v3 = (0,0,c)
      where gamma is the angle between axis a and b.
-12          Monoclinic P, unique axis b     celldm(2)=b/a
                                             celldm(3)=c/a,
                                             celldm(5)=cos(ac)
      v1 = (a,0,0), v2 = (0,b,0), v3 = (c*cos(beta),0,c*sin(beta))
      where beta is the angle between axis a and c

 13          Monoclinic base-centered        celldm(2)=b/a
                                             celldm(3)=c/a,
                                             celldm(4)=cos(ab)
      v1 = (  a/2,         0,                -c/2),
      v2 = (b*cos(gamma), b*sin(gamma), 0),
      v3 = (  a/2,         0,                  c/2),
      where gamma is the angle between axis a and b

 14          Triclinic                       celldm(2)= b/a,
                                             celldm(3)= c/a,
                                             celldm(4)= cos(bc),
                                             celldm(5)= cos(ac),
                                             celldm(6)= cos(ab)
      v1 = (a, 0, 0),
      v2 = (b*cos(gamma), b*sin(gamma), 0)
      v3 = (c*cos(beta),  c*(cos(alpha)-cos(beta)cos(gamma))/sin(gamma),
           c*sqrt( 1 + 2*cos(alpha)cos(beta)cos(gamma)
                     - cos(alpha)^2-cos(beta)^2-cos(gamma)^2 )/sin(gamma) )
  where alpha is the angle between axis b and c
         beta is the angle between axis a and c
        gamma is the angle between axis a and b
         

number of atoms in the unit cell
         

number of types of atoms in the unit cell
         

number of electronic states (bands) to be calculated.
Note that in spin-polarized calculations the number of
k-point, not the number of bands per k-point, is doubled
         

total charge of the system. Useful for simulations with charged cells.
By default the unit cell is assumed to be neutral (tot_charge=0).
tot_charge=+1 means one electron missing from the system,
tot_charge=-1 means one additional electron, and so on.

In a periodic calculation a compensating jellium background is
inserted to remove divergences if the cell is not neutral.
         

total majority spin charge - minority spin charge.
Used to impose a specific total electronic magnetization.
If unspecified, the tot_magnetization variable is ignored
and the electronic magnetization is determined by the
occupation numbers (see card OCCUPATIONS) read from input.
         

kinetic energy cutoff (Ry) for wavefunctions
         

kinetic energy cutoff (Ry) for charge density and potential
For norm-conserving pseudopotential you should stick to the
default value, you can reduce it by a little but it will
introduce noise especially on forces and stress.
If there are ultrasoft PP, a larger value than the default is
often desirable (ecutrho = 8 to 12 times ecutwfc, typically).
PAW datasets can often be used at 4*ecutwfc, but it depends
on the shape of augmentation charge: testing is mandatory.
The use of gradient-corrected functional, especially in cells
with vacuum, or for pseudopotential without non-linear core
correction, usually requires an higher values of ecutrho
to be accurately converged.
         

a string describing the occupation of the electronic states.
In the case of conjugate gradient style of minimization
of the electronic states, if occupations is set to 'ensemble',
this allows ensemble DFT calculations for metallic systems
         

parameter for the smearing function, only used for ensemble DFT
calculations
         

a string describing the kind of occupations for electronic states
in the case of ensemble DFT (occupations == 'ensemble' );
now only Fermi-Dirac ('fd') case is implemented
         

nspin = 1 :  non-polarized calculation (default)

nspin = 2 :  spin-polarized calculation, LSDA
             (magnetization along z axis)
         

ecfixed, qcutz, q2sigma:  parameters for modified functional to be
used in variable-cell molecular dynamics (or in stress calculation).
"ecfixed" is the value (in Rydberg) of the constant-cutoff;
"qcutz" and "q2sigma" are the height and the width (in Rydberg)
of the energy step for reciprocal vectors whose square modulus
is greater than "ecfixed". In the kinetic energy, G^2 is
replaced by G^2 + qcutz * (1 + erf ( (G^2 - ecfixed)/q2sigma) )
See: M. Bernasconi et al, J. Phys. Chem. Solids 56, 501 (1995)
         

Exchange-correlation functional: eg 'PBE', 'BLYP' etc
See Modules/funct.f90 for allowed values.
Overrides the value read from pseudopotential files.
Use with care and if you know what you are doing!

Use 'PBE0' to perform hybrid functional calculation using Wannier functions.
Allowed calculation: 'cp-wf' and 'vc-cp-wf'
See CP specific user manual for further guidance (or in CPV/Doc/user_guide.tex)
and examples in CPV/examples/EXX-wf-example.
Also see related keywords starting with exx_.
         

Fraction of EXX for hybrid functional calculations. In the case of
input_dft='PBE0', the default value is 0.25.
         

lda_plus_u = .TRUE. enables calculation with LDA+U
                  ("rotationally invariant"). See also Hubbard_U.
                  Anisimov, Zaanen, and Andersen, PRB 44, 943 (1991);
                  Anisimov et al., PRB 48, 16929 (1993);
                  Liechtenstein, Anisimov, and Zaanen, PRB 52, R5467 (1994);
                  Cococcioni and de Gironcoli, PRB 71, 035105 (2005).
         

Hubbard_U(i): parameter U (in eV) for LDA+U calculations.
Currently only the simpler, one-parameter LDA+U is
implemented (no "alpha" or "J" terms)
         

Type of Van der Waals correction. Allowed values:

   'grimme-d2', 'Grimme-D2', 'DFT-D', 'dft-d': semiempirical Grimme's DFT-D2.
    Optional variables: "london_s6", "london_rcut"
    S. Grimme, J. Comp. Chem. 27, 1787 (2006),
    V. Barone et al., J. Comp. Chem. 30, 934 (2009).

    'TS', 'ts', 'ts-vdw', 'ts-vdW', 'tkatchenko-scheffler': Tkatchenko-Scheffler
     dispersion corrections with first-principle derived C6 coefficients
     Optional variables: "ts_vdw_econv_thr", "ts_vdw_isolated"
     See A. Tkatchenko and M. Scheffler, Phys. Rev. Lett. 102, 073005 (2009)

    'XDM', 'xdm': Exchange-hole dipole-moment model. Optional variables: "xdm_a1", "xdm_a2"
     (implemented in PW only)
     A. D. Becke and E. R. Johnson, J. Chem. Phys. 127, 154108 (2007)
      A. Otero de la Roza, E. R. Johnson, J. Chem. Phys. 136, 174109 (2012)

Note that non-local functionals (eg vdw-DF) are NOT specified here but in "input_dft"
         

global scaling parameter for DFT-D. Default is good for PBE.
         

cutoff radius (a.u.) for dispersion interactions
         

OBSOLESCENT, same as vdw_corr='TS'
         

Optional: controls the convergence of the vdW energy (and forces). The default value
is a safe choice, likely too safe, but you do not gain much in increasing it
         

Optional: set it to .TRUE. when computing the Tkatchenko-Scheffler vdW energy
for an isolated (non-periodic) system.
         

Used to perform calculation assuming the system to be
isolated (a molecule of a clustr in a 3D supercell).

Currently available choices:

'none' (default): regular periodic calculation w/o any correction.

'makov-payne', 'm-p', 'mp' : the Makov-Payne correction to the
         total energy is computed.
         Theory:
         G.Makov, and M.C.Payne,
         "Periodic boundary conditions in ab initio
         calculations" , Phys.Rev.B 51, 4014 (1995)
         

maximum number of iterations in a scf step
         

set how electrons should be moved
'none'    : electronic degrees of freedom (d.o.f.) are kept fixed
'sd'      : steepest descent algorithm is used to minimize
          electronic d.o.f.
'damp'    : damped dynamics is used to propagate electronic d.o.f.
'verlet'  : standard Verlet algorithm is used to propagate
          electronic d.o.f.
'cg'      : conjugate gradient is used to converge the
          wavefunction at each ionic step. 'cg' can be used
          interchangeably with 'verlet' for a couple of ionic
          steps in order to "cool down" the electrons and
          return them back to the Born-Oppenheimer surface.
          Then 'verlet' can be restarted again. This procedure
          is useful when electronic adiabaticity in CP is lost
          yet the ionic velocities need to be preserved.
         

Convergence threshold for selfconsistency:
estimated energy error < conv_thr
         

frequency in iterations for which the conjugate-gradient algorithm
for electronic relaxation is restarted
         

Amplitude of the finite electric field (in a.u.;
1 a.u. = 51.4220632*10^10 V/m). Used only if tefield=.TRUE.
         

direction of the finite electric field (only if tefield == .TRUE.)
In the case of a PARALLEL calculation only the case epol==3
is implemented
         

effective electron mass in the CP Lagrangian, in atomic units
( 1 a.u. of mass = 1/1822.9 a.m.u. = 9.10939 * 10^-31 kg )
         

mass cut-off (in Rydberg) for the Fourier acceleration
effective mass is rescaled for "G" vector components with
kinetic energy above "emass_cutoff"
         

selects the orthonormalization method for electronic wave
functions
'ortho'        : use iterative algorithm - if it doesn't converge,
                 reduce the timestep, or use options ortho_max
                 and ortho_eps, or use Gram-Schmidt instead just
                 to start the simulation
'Gram-Schmidt' : use Gram-Schmidt algorithm - to be used ONLY in
                 the first few steps.
                 YIELDS INCORRECT ENERGIES AND EIGENVALUES.
         

tolerance for iterative orthonormalization
meaningful only if orthogonalization = 'ortho'
         

maximum number of iterations for orthonormalization
meaningful only if orthogonalization = 'ortho'
         

damping frequency times delta t, optimal values could be
calculated with the formula :
         SQRT( 0.5 * LOG( ( E1 - E2 ) / ( E2 - E3 ) ) )
where E1, E2, E3 are successive values of the DFT total energy
in a steepest descent simulations.
meaningful only if " electron_dynamics = 'damp' "
         

'zero'      : restart setting electronic velocities to zero
'default'   : restart using electronic velocities of the
            previous run
         

'nose'            : control electronic temperature using Nose
                  thermostat. See also "fnosee" and "ekincw".
'rescaling'       : control electronic temperature via velocities
                  rescaling.
'not_controlled'  : electronic temperature is not controlled.
         

value of the average kinetic energy (in atomic units) forced
by the temperature control
meaningful only with " electron_temperature /= 'not_controlled' "
         

oscillation frequency of the nose thermostat (in terahertz)
meaningful only with " electron_temperature = 'nose' "
         

'atomic': start from superposition of atomic orbitals
          (not yet implemented)


'random': start from random wfcs. See "ampre".
         

if .TRUE. perform a conjugate gradient minimization of the
electronic states for every ionic step.
It requires Gram-Schmidt orthogonalization of the electronic
states.
         

maximum number of conjugate gradient iterations for
conjugate gradient minimizations of electronic states
         

small step used in the  conjugate gradient minimization
of the electronic states.
         

number of internal cycles for every conjugate gradient
iteration only for ensemble DFT
         

frequency in iterations at which a full inner cycle, only
for cold smearing, is performed
         

step for inner cycle with cold smearing, used when a not full
cycle is performed
         

a number <= 1, very close to 1: the damping in electronic
damped dynamics is multiplied at each time step by "grease"
(avoids overdamping close to convergence: Obsolete ?)
grease = 1 : normal damped dynamics
         

amplitude of the randomization ( allowed values: 0.0 - 1.0 )
meaningful only if " startingwfc = 'random' "
         

 Specify the type of ionic dynamics.

 For constrained dynamics or constrained optimisations add the
 CONSTRAINTS card (when the card is present the SHAKE algorithm is
                   automatically used).
'none'    : ions are kept fixed
'sd'      : steepest descent algorithm is used to minimize ionic
            configuration
'cg'      : conjugate gradient algorithm is used to minimize ionic
            configuration
'damp'    : damped dynamics is used to propagate ions
'verlet'  : standard Verlet algorithm is used to propagate ions
         

'default '  : if restarting, use atomic positions read from the
              restart file; in all other cases, use atomic
              positions from standard input.

'from_input' : restart the simulation with atomic positions read
              from standard input, even if restarting.
         

initial ionic velocities
'default'     : restart the simulation with atomic velocities read
                from the restart file
'change_step' : restart the simulation with atomic velocities read
                from the restart file, with rescaling due to the
                timestep change, specify the old step via tolp
                as in tolp = 'old_time_step_value' in au
'random'      : start the simulation with random atomic velocities
'from_input'  : restart the simulation with atomic velocities read
                from standard input - see card 'ATOMIC_VELOCITIES'
                BEWARE: works only if restart_mode='from_scratch',
                tested only with electrons_dynamics='cg'
'zero'        : restart the simulation with atomic velocities set
                to zero
         

damping frequency times delta t, optimal values could be
  calculated with the formula :
  SQRT( 0.5 * LOG( ( E1 - E2 ) / ( E2 - E3 ) ) )
  where E1, E2, E3 are successive values of the DFT total energy
  in a steepest descent simulations.
  meaningful only if " ion_dynamics = 'damp' "
         

ion_radius(i): pseudo-atomic radius of the i-th atomic species
used in Ewald summation. Typical values: between 0.5 and 2.
Results should NOT depend upon such parameters if their values
are properly chosen. See also "iesr".
         

The real-space contribution to the Ewald summation is performed
on iesr*iesr*iesr cells. Typically iesr=1 is sufficient to have
converged results.
         

number of electronic steps per ionic step.
         

This keyword is useful when simulating the dynamics and/or the
thermodynamics of an isolated system. If set to true the total
torque of the internal forces is set to zero by adding new forces
that compensate the spurious interaction with the periodic
images. This allows for the use of smaller supercells.

BEWARE: since the potential energy is no longer consistent with
the forces (it still contains the spurious interaction with the
repeated images), the total energy is not conserved anymore.
However the dynamical and thermodynamical properties should be
in closer agreement with those of an isolated system.
Also the final energy of a structural relaxation will be higher,
but the relaxation itself should be faster.
         

'nose'           : control ionic temperature using Nose-Hoover
                   thermostat  see parameters "fnosep", "tempw",
                   "nhpcl", "ndega", "nhptyp"
'rescaling'      : control ionic temperature via velocities
                   rescaling. see parameter "tolp"
'not_controlled' : ionic temperature is not controlled
         

value of the ionic temperature (in Kelvin) forced by the
temperature control.
meaningful only with " ion_temperature /= 'not_controlled' "
or when the initial velocities are set to 'random'
"ndega" controls number of degrees of freedom used in
temperature calculation
         

oscillation frequency of the nose thermostat (in terahertz)
[note that 3 terahertz = 100 cm^-1]
meaningful only with " ion_temperature = 'nose' "
for Nose-Hoover chain one can set frequencies of all thermostats
( fnosep = X Y Z etc. ) If only first is set, the defaults for
the others will be same.
         

tolerance (in Kelvin) of the rescaling. When ionic temperature
differs from "tempw" more than "tolp" apply rescaling.
meaningful only with " ion_temperature = 'rescaling' "
and with ion_velocities='change_step', where it specifies
the old timestep
         

number of thermostats in the Nose-Hoover chain
currently maximum allowed is 4
         

type of the "massive" Nose-Hoover chain thermostat
nhptyp=1 uses a NH chain per each atomic type
nhptyp=2 uses a NH chain per atom, this one is useful
for extremely rapid equipartitioning (equilibration is a
different beast)
nhptyp=3 together with nhgrp allows fine grained thermostat
control
NOTE: if using more than 1 thermostat per system there will
be a common thermostat added on top of them all, to disable
this common thermostat specify nhptyp=-X instead of nhptyp=X
         

specifies which thermostat group to use for given atomic type
when >0 assigns all the atoms in this type to thermostat
labeled nhgrp(i), when =0 each atom in the type gets its own
thermostat. Finally, when <0, then this atomic type will have
temperature "not controlled". Example: HCOOLi, with types H (1), C(2), O(3), Li(4);
setting nhgrp={2 2 0 -1} will add a common thermostat for both H & C,
one thermostat per each O (2 in total), and a non-updated thermostat
for Li which will effectively make temperature for Li "not controlled"
         

these are the scaling factors to be used together with nhptyp=3 and nhgrp(i)
in order to take care of possible reduction in the degrees of freedom due to
constraints. Suppose that with the previous example HCOOLi, C-H bond is
constrained. Then, these 2 atoms will have 5 degrees of freedom in total instead
of 6, and one can set fnhscl={5/6 5/6 1. 1.}. This way the target kinetic energy
for H&C will become 6(kT/2)*5/6 = 5(kT/2). This option is to be used for
simulations with many constraints, such as rigid water with something else in there
         

number of degrees of freedom used for temperature calculation
ndega <= 0 sets the number of degrees of freedom to
[3*nat-abs(ndega)], ndega > 0 is used as the target number
         

If .TRUE. randomize ionic positions for the
atomic type corresponding to the index.
         

amplitude of the randomization for the atomic type corresponding
to the index i ( allowed values: 0.0 - 1.0 ).
meaningful only if " tranp(i) = .TRUE.".
         

same as "grease", for ionic damped dynamics.
         

'default'      : restart the simulation with cell parameters read
               from the restart file or "celldm" if
               "restart = 'from_scratch'"
'from_input'   : restart the simulation with cell parameters
               from standard input.
               ( see the card 'CELL_PARAMETERS' )
         

set how cell should be moved
'none'      : cell is kept fixed
'sd'        : steepest descent algorithm is used to optimise the
              cell
'damp-pr'   : damped dynamics is used to optimise the cell
              ( Parrinello-Rahman method ).
'pr'        : standard Verlet algorithm is used to propagate
              the cell ( Parrinello-Rahman method ).
         

'zero'      : restart setting cell velocity to zero
'default'   : restart using cell velocity of the previous run
         

damping frequency times delta t, optimal values could be
calculated with the formula :
         SQRT( 0.5 * LOG( ( E1 - E2 ) / ( E2 - E3 ) ) )
where E1, E2, E3 are successive values of the DFT total energy
in a steepest descent simulations.
meaningful only if " cell_dynamics = 'damp' "
         

Target pressure [KBar] in a variable-cell md or relaxation run.
         

Fictitious cell mass [amu] for variable-cell simulations
(both 'vc-md' and 'vc-relax')
         

Used in the construction of the pseudopotential tables.
It should exceed the maximum linear contraction of the
cell during a simulation.
         

'nose'            : control cell temperature using Nose thermostat
                    see parameters "fnoseh" and "temph".
'rescaling'       : control cell temperature via velocities
                    rescaling.
'not_controlled'  : cell temperature is not controlled.
         

value of the cell temperature (in ???) forced
by the temperature control.
meaningful only with " cell_temperature /= 'not_controlled' "
         

oscillation frequency of the nose thermostat (in terahertz)
meaningful only with " cell_temperature = 'nose' "
         

same as "grease", for cell damped dynamics
         

Select which of the cell parameters should be moved:

all     = all axis and angles are moved
x       = only the x component of axis 1 (v1_x) is moved
y       = only the y component of axis 2 (v2_y) is moved
z       = only the z component of axis 3 (v3_z) is moved
xy      = only v1_x and v2_y are moved
xz      = only v1_x and v3_z are moved
yz      = only v2_y and v3_z are moved
xyz     = only v1_x, v2_y, v3_z are moved
shape   = all axis and angles, keeping the volume fixed
2Dxy    = only x and y components are allowed to change
2Dshape = as above, keeping the area in xy plane fixed
volume  = isotropic variations of v1_x, v2_y, v3_z, keeping
          the shape fixed. Should be used only with ibrav=1.
         

.true. for finite pressure calculations
         

.true. for finite surface tension calculations
         

external pressure in GPa
         

.true. for variable pressure calculations
pressure changes linearly with time:
Delta_P = (P_fin - P_in)/nstep
         

only if pvar = .true.
initial value of the external pressure (GPa)
         

only if pvar = .true.
final value of the external pressure (GPa)
         

Surface tension (in a.u.; typical values 1.d-4 - 1.d-3)
         

threshold parameter which defines the electronic charge density
isosurface to compute the 'quantum' volume of the system
(typical values: 1.d-4 - 1.d-3)
(corresponds to alpha in PRL 94 145501 (2005))
         

thikness of the external skin of the electronic charge density
used to compute the 'quantum' surface
(typical values: 1.d-4 - 1.d-3; 50% to 100% of rho_thr)
(corresponds to Delta in PRL 94 145501 (2005))
         

If dynamics will be done in the presence of a field
         

Whether to turn on the field adiabatically (adiabatic switch)
if true, then nbeg is set to 0.
         

No. of iterations over which the field will be turned on
to its final value. Starting value is 0.0
If sw_len < 0, then it is set to 1.
If you want to just optimize structures on the presence of a
field, then you may set this to 1 and run a regular geometry
optimization.
         

Localization algorithm for Wannier function calculation:
wfsd=1  Damped Dynamics
wfsd=2  Steepest-Descent / Conjugate-Gradient
wfsd=3  Jocobi Rotation
Remember, this is consistent with all the calwf options
as well as the tolw (see below).
Not a good idea to Wannier dynamics with this if you are
using restart='from_scratch' option, since the spreads
converge fast in the beginning and ortho goes bananas.
         

The minimum step size to take in the SD/CG direction
         

The maximum step size to take in the SD/CG direction
The code calculates an optimum step size, but that may be
either too small (takes forever to converge)  or too large
(code goes crazy) . This option keeps the step size between
wfdt and maxwfdt. In my experience 0.1 and 0.5 work quite
well. (but don't blame me if it doesn't work for you)
         

Number of iterations to do for Wannier convergence.
         

Out of a total of NIT iterations, NSD will be Steepest-Descent
and ( nit - nsd ) will be Conjugate-Gradient.
         

Fictitious mass of the A matrix used for obtaining
maximally localized Wannier functions. The unitary
transformation matrix U is written as exp(A) where
A is a anti-hermitian matrix. The Damped-Dynamics is performed
in terms of the A matrix, and then U is computed from A.
Usually a value between 1500 and 2500 works fine, but should
be tested.
         

Damping coefficient for Damped-Dynamics.
         

Number of Damped-Dynamics steps to be performed per CP
iteration.
         

Convergence criterion for localization.
         

Whether to adapt the damping parameter dynamically.
         

Wannier Function Options, can be 1,2,3,4,5

1. Output the Wannier function density, nwf and wffort
   are used for this option. see below.
2. Output the Overlap matrix O_i,j=<w_i|exp{iGr}|w_j>. O is
   written to unit 38. For details on how O is constructed,
   see below.
3. Perform nsteps of Wannier dynamics per CP iteration, the
   orbitals are now Wannier Functions, not Kohn-Sham orbitals.
   This is a Unitary transformation of the occupied subspace
   and does not leave the CP Lagrangian invariant. Expectation
   values remain the same. So you will **NOT** have a constant
   of motion during the run. Don't freak out, its normal.
4. This option starts for the KS states and does 1 CP iteration
   and nsteps of Damped-Dynamics to generate  maximally
   localized wannier functions. Its useful when you have the
   converged KS groundstate and want to get to the converged
   Wannier function groundstate in 1 CP Iteration.
5. This option is similar to calwf 1, except that the output is
   the Wannier function/wavefunction, and not the orbital
   density. See nwf below.
         

This option is used with calwf 1 and calwf 5. with calwf=1,
it tells the code how many Orbital densities are to be
output. With calwf=5, set this to 1(i.e calwf=5 only writes
one state during one run. so if you want 10 states, you have
to run the code 10 times). With calwf=1, you can print many
orbital densities in a single run.
See also the PLOT_WANNIER card for specifying the states to
be printed.
         

This tells the code where to dump the orbital densities. Used
 only with CALWF=1. for e.g. if you want to print 2 orbital
 densities, set calwf=1, nwf=2 and wffort to an appropriate
 number (e.g. 40) then the first orbital density will be
 output to fort.40, the second to fort.41 and so on. Note that
 in the current implementation, the following units are used
 21,22,24,25,26,27,28,38,39,77,78 and whatever you define as
 ndr and ndw. so use number other than these.
         

Output the charge density (g-space) and the list of g-vectors
This is useful if you want to reconstruct the electrostatic
potential using the Poisson equation. If .TRUE. then the
code will output the g-space charge density and the list
if G-vectors, and STOP.
Charge density is written to : CH_DEN_G_PARA.ispin (1 or 2
depending on the number of spin types) or CH_DEN_G_SERL.ispin
depending on if the code is being run in parallel or serial
G-vectors are written to G_PARA or G_SERL.
         

An initial guess on the maximum number of neighboring (overlapping) Wannier functions.
         

Radial cutoff distance (in bohr) for including overlapping Wannier function pairs
in EXX calculations.
         

Poisson solver convergence criterion during computation of the EXX potential.
         

Radial cutoff distance (in bohr) to compute the self EXX energy.
This distance determines the radius of the Poisson sphere centered at
a given Wannier function center, and should be large enough to cover
the majority of the orbital charge density.
         

Radial cutoff distance (in bohr) to compute the pair EXX energy.
This distance determines the radius of the Poisson sphere centered at
the midpoint of two overlapping Wannier functions, and should be
large enough to cover the majority of the orbital overlap charge density.
This parameter can generally be chosen as smaller than exx_ps_rcut_self.
         

Radial cutoff distance (in bohr) for the multipole-expansion sphere
centered at a given Wannier function center.
The far-field self EXX potential in this sphere is generated with
multipole expansion of the orbital charge density.
         

Radial cutoff distance (in bohr) for the multipole-expansion sphere
centered at the midpoint of two overlapping Wannier functions.
The far-field pair EXX potential in this sphere is generated with
a multipole expansion of the orbital overlap charge density.
This parameter can generally be chosen as smaller than exx_me_rcut_self.