# Explanations of input files (dielectric function of crystalline silicon)

## Contents

### &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 sysname = 'C2H2' 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
/


iperiodic = 3 indicates that three dimensional periodic boundary condition (bulk crystal) is assumed. al = 10.26d0, 10.26d0, 10.26d0 specifies the lattice constans of the unit cell. nstate = 32 indicates the number of Kohn-Sham orbitals to be solved. nelec = 32 indicate the number of valence electrons in the system. nelem = 1 and natom = 8 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
/


izatom(1) = 14 indicates the atomic number of the element #1. pseudo_file(1) = 'Si_rps.dat' indicates the pseudopotential filename of element #1. lloc_ps(1) = 2 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
/


num_rgrid=12,12,12 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
/


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

### &propagation

&propagation
propagator='etrs'
/


propagator = 'etrs' 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
/


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

## &emfield

Mandatory:ae_shape1

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


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

epdir_re1(3) specify a unit vector that indicates the direction of the impulse.

 trans_longi = 'tr' 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
/


nenergy=1000 specifies the number of energy steps, and de=0.001 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.