How to run single point energy calculation on Mg2Si in VASP

Question

I want to do single point energy calculations in VASP for $\ce{Mg2Si}$ so what should be initial steps to do? What are tags required in INCAR sufficient to do this calculation?

I would appreciate any help.

Answer 1

I assume that you have relaxed your geometry structure. The single point energy calculation also called the self-consistent field calculation (SCFC), the central quantities outputted by it are:

• Total energy
• Charge density
• Wavefunction

In particular, the charge density and the wavefunction are the two key quantities to perform non-self-consistent calculations, such as band structure, the density of states so on.

A general INCAR for SCF in VASP can be:

    System=:
    ISTART=0        #startjob: 0-new 1-cont 2-samecut
    ICHARG=2        #charge: 1-file 2-atom 10-const
    ENCUT=450       #energy cutoff in eV
    EDIFF=1E-5      #stopping-criterion for electronic upd.
    NELM=300        #nr. of electronic steps
    ISMEAR=0        #part. occupancies: -5 Blochl -4-tet -1-fermi 0-gaus 0 MP
    SIGMA=0.01      #broadening in eV -4-tet -1-fermi 0-gaus
    IALGO=38        #algorithm
    #LREAL=Auto     #Auto for large cell, False for small cell

    #Magnetic and SOC related tags
    #ISPIN=2              #spin polarized calculation (2-yes 1-no)
    #MAGMOM=15*0 17*0     #initial magnetization
    #LSORBIT=.TRUE.       #switches on SOC and sets LNONCOLLINEAR= .TRUE.
    #SAXIS= 0 0 1         #quantisation axis for spin
    #ISYM=0               #symmetry: 0-nonsym 1-usesym

    Output:
    LCHARG=.True.         #create CHGCAR
    LWAVE=.True.          #create WAVECAR

If you want firstly to relax the structure, you should add the following tags:

   #Dynamic:
   ISIF=3
   IBRION=2
   NSW=300 
   EDIFFG=-0.005

You can check the meaning of each tag in INCAR from vaspwiki.

Hope it helps.