# Explanations of input files (C2H2 molecule under a pulsed electric field)

## required and recommended variables

### &units

Mandatory: none

&units
unit_system='A_eV_fs'
/


This namelist specifies the unit system to be used in the input file. If you do not specify it, atomic unit will be used. See Input variables#&units for detail.

### &calculation

Mandatory: calc_mode

&calculation
calc_mode = 'RT'
/


This indicates that the real time (RT) calculation is carried out in the present job. See Tutorial-v.1.0.0#&calculation for detail.

### &control

Mandatory: none

&control
sysname = 'C2H2'
/


'C2H2' defined by sysname = 'C2H2' will be used in the filenames of output files.

### &system

Mandatory: iperiodic, al, nstate, nelem, natom

&system
iperiodic = 0
al = 16d0, 16d0, 16d0
nstate = 5
nelem = 2
natom = 4
nelec = 10
/


These namelists and their values should be the same as those used in the ground state calculation. See Explanations of input files (ground state of C2H2 molecule)#&system.

### &pseudo

Mandatory: pseudo_file, izatom

&pseudo
izatom(1)=6
izatom(2)=1
pseudo_file(1)='C_rps.dat'
pseudo_file(2)='H_rps.dat'
lmax_ps(1)=1
lmax_ps(2)=0
lloc_ps(1)=1
lloc_ps(2)=0
/


These namelists and their values should be the same as those used in the ground state calculation. See Explanations of input files (ground state of C2H2 molecule)#&pseudo.

### &tgrid

Mandatory: dt, Nt

&tgrid
dt=1.25d-3
nt=4800
/


dt=1.25d-3 specifies the time step of the time evolution calculation. Nt=4800 specifies the number of time steps in the calculation.

### &emfield

Mandatory: ae_shape1, epdir_re1, {rlaser_int1 or amplitude1}, omega1, pulse_tw1, phi_cep1

&emfield
ae_shape1 = 'Ecos2'
epdir_re1 = 0.d0,0.d0,1.d0
rlaser_int_wcm2_1 = 1.d8
omega1=9.28d0
pulse_tw1=6.d0
phi_cep1=0.75d0
/


ae_shape1 = 'Ecos2' indicates that the envelope of the pulsed electric field has a cos^2 shape.

epdir_re1 = 0.d0,0.d0,1.d0 specifies the real part of the unit polarization vector of the pulsed electric field. Using the real polarization vector, it describes a linearly polarized pulse.

laser_int_wcm2_1 = 1.d8 specifies the maximum intensity of the applied electric field in unit of W/cm^2.

omega1=9.26d0 specifies the average photon energy (frequency multiplied with hbar).

pulse_tw1=6.d0 specifies the pulse duration. Note that it is not the FWHM but a full duration of the cos^2 envelope.

phi_cep1=0.75d0 specifies the carrier envelope phase of the pulse. As noted above, 'phi_cep1' must be 0.75 (or 0.25) if one employs 'Ecos2' pulse shape, since otherwise the time integral of the electric field does not vanish.

See Tutorial-v.1.0.0#&emfield for details.

### &atomic_coor

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

&atomic_coor
'C'    0.000000    0.000000    0.599672  1
'H'    0.000000    0.000000    1.662257  2
'C'    0.000000    0.000000   -0.599672  1
'H'    0.000000    0.000000   -1.662257  2
/


Cartesian coordinates of atoms. The first column indicates the element. Next three columns specify Cartesian coordinates of the atoms. The number in the last column labels the element. They must be the same as those in the ground state calculation.