Explanation of input files (pulsed-light propagation through a silicon thin film)

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&calculation

Mandatory: calc_mode 

 &calculation
   calc_mode = 'GS_RT'
   use_ms_maxwell = 'y'
 /

calc_mode = 'GS_RT' indicates that the ground state (GS) and the real time (RT) calculations are carried out sequentially in the present job. use_ms_maxwell = 'y' indicates the multi-scale Maxwell - TDDFT calculation. 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

 &system
   iperiodic = 3
   al = 10.26d0,10.26d0,10.26d0
   isym = 8 
   crystal_structure = 'diamond'
   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. isym = 8 and crystal_structure = 'diamond', which indicates that the spatial symmetry of the unit cell is used in the calculation. Although the use of the symmetry substantially reduces the computational cost, it should be used very carefully. At present, the spatial symmetry has been implemented only for the case of the diamond structure. 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.l

&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 = 2,2,2
/

&tgrid

&tgrid 

nt=4000
dt=0.08

/

dt=0.08 specifies the time step of the time evolution calculation. nt=4000 specifies the number of time steps in the calculation.

&propagation

&propagation
  propagator='middlepoint'
/

propagator = 'middlepoint' indicates that Hamiltonian at midpoint of two-times is used. 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

 &emfield
   ae_shape1 = 'Acos2'
   rlaser_int_wcm2_1 = 1d12
   pulse_tw1 = 441.195136248d0
   omega1 = 0.05696145187d0
   epdir_re1 = 0.,0.,1.
 /

This namelist specifies the pulsed electric field applied to the system

ae_shape1 = 'Acos2' specifies the envelope of the pulsed electric field, cos^2 envelope for the vector potential.

epdir_re1 = 0.,0.,1. specify the real part of the unit polarization vector of the pulsed electric field. Specifying only the real part, it describes a linearly polarized pulse.

laser_int_wcm2_1 = 1d12 specifies the maximum intensity of the applied electric field in unit of W/cm^2.

omega1=0.05696145187d0 specifies the average photon energy (frequency multiplied with hbar).

pulse_tw1=441.195136248d0 specifies the pulse duration. Note that it is not the FWHM but a full duration of the cos^2 envelope.

See Input variables#&emfield for detail.

&multiscale

This namelist specifies information necessary for Maxwell - TDDFT multiscale calculations. 

&multiscale
  fdtddim = '1D'
  twod_shape = 'periodic'
  nx_m  = 4
  ny_m  = 1
  hX_m = 250d0
  nxvacl_m = -2000
  nxvacr_m = 256
/

fdtddim specifies the spatial dimension of the macro system. fdtddim='1D' indicates that one-dimensional equation is solved for the macroscopic vector potential.

nx_m = 4 specifies the number of the macroscopic grid points in for x-direction in the spatial region where the material exists.

hx_m = 250d0 specifies the grid spacing of the macroscopic grid in x-direction.

nxvacl_m = -2000 and nxvacr_m = 256 indicate the number of grid points in the vacuum region, nxvacl_m for the left and nxvacr_m for the right from the surface of the material.

&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.

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