View source for Explanations of input files (dielectric function of crystalline silicon)

=== &calculation ===

Mandatory: calc_mode

 &calculation
   calc_mode = 'GS_RT'
 /

This indicates that the ground state (GS) and the real time (RT) calculations are carried out sequentially in the present job. See [[Input variables#&calculation]] for detail.

=== &control ===

Mandatory: none

 &control
   sysname = 'Si'
 /

'Si' defined by <code>sysname = 'C2H2'</code> will be used in the filenames of output files.

=== &system ===

Mandatory: periodic, al, state, nelem, natom

 &system
   iperiodic = 3
   al = 10.26d0,10.26d0,10.26d0
   nstate = 32
   nelec = 32
   nelem = 1
   natom = 8
 /

<code>iperiodic = 3</code> indicates that three dimensional periodic boundary condition (bulk crystal) is assumed.
<code>al = 10.26d0, 10.26d0, 10.26d0</code> specifies the lattice constans of the unit cell.
<code>nstate = 32</code> indicates the number of Kohn-Sham orbitals to be solved. 
<code>nelec = 32</code> indicate the number of valence electrons in the system.
<code>nelem = 1</code> and <code>natom = 8</code> indicate the number of elements and the number of atoms in the system, respectively.
See [[Input variables#&system]] for more information.

=== &pseudo ===

 &pseudo
   izatom(1)=14
   pseudo_file(1) = './Si_rps.dat'
   lloc_ps(1)=2
 /

<code>izatom(1) = 14</code> indicates the atomic number of the element #1.
<code>pseudo_file(1) = 'Si_rps.dat'</code> indicates the  pseudopotential filename of element #1. 
<code>lloc_ps(1) = 2</code> indicate the angular momentum of the pseudopotential that will be treated as local.

=== &functional ===

 &functional
   xc = 'PZ'
 /

This indicates that the adiabatic local density approximation with the Perdew-Zunger functional is used. We note that meta-GGA functionals that reasonably reproduce the band gap of various insulators may also be used in the calculation of periodic systems. See [[Input variables#&functional]] for detail.

=== &rgrid ===

Mandatory: dl or num_rgrid

 &rgrid
   num_rgrid = 12,12,12
 /

<code>num_rgrid=12,12,12</code> specifies the number of the grids for each Cartesian direction.
See [[Input variables#&rgrid]] for more information.

=== &kgrid ===

Mandatory: none

This namelist provides grid spacing of k-space for periodic systems.

 &kgrid
   num_kgrid = 4,4,4
 /

=== &tgrid ===

 &tgrid
  nt=3000
  dt=0.16  
 /

<code>dt=0.16</code> specifies the time step of the time evolution calculation.
<code>nt=3000</code> specifies the number of time steps in the calculation.

=== &propagation ===

 &propagation
   propagator='etrs'
 /

<code>propagator = 'etrs'</code> indicates the use of enforced time-reversal symmetry propagator. See [[Input variables#&propagation]] for more information.

=== &scf ===

Mandatory: nscf

This namelists specify parameters related to the self-consistent field calculation.

 &scf
   ncg = 5
   nscf = 120
 /

<code>ncg = 5</code> is the number of conjugate-gradient iterations in solving the Kohn-Sham equation. Usually this value should be 4 or 5. <code>nscf = 120</code> is the number of scf iterations.

== &emfield ==

Mandatory:ae_shape1

 &emfield
   trans_longi = 'tr'
   ae_shape1 = 'impulse'
   epdir_re1 = 0.,0.,1.
 /

<code>as_shape1 = 'impulse'</code> indicates that a weak impulsive field is applied to all electrons at ''t=0''

<code>epdir_re1(3)</code> specify a unit vector that indicates the direction of the impulse.

<code> trans_longi = 'tr'</code> specifies the treatment of the polarization in the time evolution calculation, transverse for 'tr' and longitudinal for 'lo'. 

See [[Input variables#&emfield]] for detail.

=== &analysis ===

 &analysis
  nenergy=1000
  de=0.001
 /

<code>nenergy=1000</code> specifies the number of energy steps, and <code>de=0.001</code> specifies the energy spacing in the time-frequency Fourier transformation.

=== &atomic_red_coor ===

Mandatory: atomic_coor or atomic_red_coor (they may be provided as a separate file)

 &atomic_red_coor
  'Si'    .0      .0      .0      1
  'Si'    .25    .25    .25    1
  'Si'    .5      .0      .5      1
  'Si'    .0      .5      .5      1
  'Si'    .5      .5      .0      1
  'Si'    .75    .25   .75     1
  'Si'    .25    .75   .75     1
  'Si'    .75    .75   .25     1
 /

Cartesian coordinates of atoms are specified in a reduced coordinate system. First column indicates the element, next three columns specify reduced Cartesian coordinates of the atoms, and the last column labels the element.