# How to run single point energy calculation on Mg2Si in VASP

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.

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.

• Hi Jack, Thank you so much for your help and above answer. Feb 26, 2021 at 7:55
• @Shalini You are welcome.
– Jack
Feb 26, 2021 at 19:24