Explanations for Si response input files

Unit system

Hartree atomic units are used in this calculation by default.

&calculation

 &calculation
   calc_mode = 'GS_RT'
 /

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

&control

 &control
  sysname = 'Si'
 /

The variable sysname is set to be 'Si', which is used as 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 assumed. 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 preferred to speed up the calculation. For more infomation, see Symmetry group of crystaline. crystal_structure = 'diamond' indicate the crystal structure of the considered material. 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.

&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 filename of the pseudopotential of element 1. Lloc_ps(1) = 1 indicate the angular momentum of the pseudopotential that will be treated as local.

&functional

 &functional
   xc ='TBmBJ'
   cval = 1d0
 /

xc ='TBmBJ' specifies the type of exchange correlation potential. The TBmBJ indicates a meta-generalized gradient approximation proposed by Tran and Blaha Phys. Rev. Lett. 102, 226401 (2009). cval specifies the additional parameter of the TBmBJ potential. In the case of the silicon, cval = 1d0 is prefered to reproduce the experimentally mesured optical constants.