Explanations for Si ms input files

Unit system

Hartree atomic units are employed in this calculation by default.

&calculation

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

The variable calc_mode is set to be 'GS_RT' mode, which executes the ground state (GS) and real-time (RT) calculation with single calculation task.

use_ms_maxwell='y'

indicates the multiscale Maxwell-TDDFT calculation mode.

&control

 &control
   sysname = 'Si'
 /

The variable sysname is set to be 'Si', which is the filename prefix of the outputs.

&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 supposed. al = 10.26d0, 10.26d0, 10.26d0 specifies the lattice constans of the unit cell crystaline. The variable isym indicates the symmetry in the unit cell. Considering the bulk silicon crystal with the applied electric field parallel to the one lattice axis, isym = 8 is desirable to speed up the calculation. For more information, see Symmetry group of crystalline. crystal_structure = 'diamond' indicate the crystal structure of the considered material. nstate = 32 indicates the number of Kohn-Sham orbitals in the computation. nelec = 32 is the number of valence electrons in the system. nelem = 1 and natom = 8 is the number of elements and the number of atoms in the system, respectively.

&pseudo

 &pseudo
   iZatom(1)=14
   pseudo_file(1) = './Si_rps.dat'
   Lloc_ps(1)=2
 /

iZatom(1) = 14 is the number of atoms for the element 1. pseudo_file(1) = 'Si_rps.dat' is the filename of the pseudopotential of element 1. Lloc_ps(1) = 1 indicate the angular momentum of the pseudopotential.

&functional

 &functional
   xc ='PZ'
 /

xc ='PZ' specifies the type of exchange correlation potential as LDA.

&rgrid

 &rgrid
   num_rgrid = 12,12,12
 /

num_rgrid=12,12,12 specifies number of the real space grids for single crystal calculation.

&kgrid

 &kgrid
   num_kgrid = 2,2,2
 /

num_kgrid=2,2,2 specifies number of the k-space grids for single crystal calculation.

&tgrid

&tgrid

nt=4000
dt=0.08  

/

dt=0.16 sets the time step of the time-evolution calculations. Nt=3000 is the number of time steps in the calculation.

&propagation

propagation

 propagator='middlepoint'

/

propagation='middlepoint' specifies the numerical mathod of the time-evolution of the wave function.

&scf

 &scf
   ncg = 5
   nscf = 100
 /

ncg = 5 is the number of conjucate gradient step in the single scf calculation, and nscf = 100 specifies the number of the SCF step.

&emfield

 &emfield
   ae_shape1 = 'Acos2'
   rlaser_int1 = 1d12
   pulse_tw1 = 441.195136248d0
   omega1 = 0.05696145187d0
   epdir_re1 = 0.,0.,1.
 /

ae_shape1 = 'Acos2' specifies the pulse shape of the electric field, having cos-square envelope. laser_int1 specifies maximum intensity of the applied electric field in unit of W/cm^2. epdir_re1 = 0,0,1 identifies the unit vector of polarization direction. Specifying the real part of the polarization vector by 'epdir_re1', linear polarization is assumed. Using both the real ('epdir_re1') and imaginary ('epdir_im1') parts of the polarization vector, circularly (and general ellipsoidally) polarized pulses may also be described.

omega1 specifies photon energy (frequency multiplied with hbar). pulse_tw1 sets the pulse duration. Note that it is not FWHM but a full duration of the sine-square envelope. phi_cep1 specifies the carrier envelope phase of the pulse. It is possible to have two pulses simultaneously to simulate pump-probe experiments, adding information for two pulses. The time delay can be indicated using the variable 't1_t2'.

&multiscale

 &multiscale
   fdtddim = '1D'
   twod_shape = 'periodic'
   nx_m  = 4
   ny_m  = 1
   hX_m = 250d0
   nksplit = 2
   nxysplit = 1
   nxvacl_m = -2000
   nxvacr_m = 256
 /

fdtddim specifies the dimension of the macro system. In the case of fdtddim='1D', the one-dimensional light propagation in the slab region. twod_shape = 'periodic' specifies the boundary condition of the EM field. nx_m, ny_m is the number of the macroscopic grids for the x and y-direction, respectively. nxvacl_m, nxvacr_m indicates the number of the additional cells connected on the left-side and right-side of the material's surface.

&atomic_coor

&atomic_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
/

List of atomic coordinates. Last column corresponds to kinds of elements.