# VASP input file for formation energy calculation

I want to calculate the formation energy of $$\ce{Mg2Si}$$ using VASP. What should be the initial steps to perform this run? What INCAR tags are required? Any help would be appreciated. Thanks!

• +1 But please take a look at the edits I made, especially the tags that I added and the $\ce{ }$ that I used for the formatting of your chemical formula. – Nike Dattani Mar 8 at 15:54
• @NikeDattani Thanks for editing my question and make it more clear – Shalini Mar 8 at 16:56

If your structure is relaxed. The total energy can be calculated with a self-consistent calculation.

An INCAR template you may refer to:

System:
ISTART=0
ICHARG=2
ENCUT=500
EDIFF=1E-6
NELM=300
ISMEAR=0
SIGMA=0.05
IALGO=38

##Spin-related
#ISPIN=2
#MAGMOM=17*0
#LSORBIT=.TRUE.
#SAXIS= 0 0 1
#ISYM=0

##Output:
LCHARG=.TRUE.
LWAVE=.TRUE.


PS: For the formation energy calculation, you need to find the lowest-energy configuration of bulk Mg and Si.

And this post also may helpful: How to calculate the formation energy of a monolayer using VASP?

Hope it helps.

• Hi Thank you so much for reply . Could you please tell should I take primitive cell for finding lowest ground state energy or conventional cell for Mg2Si , Mg, Si ? I am following one question asked here only where formation energy is calculated for MgCu2 where user take conventional cell of 24 atoms . – Shalini Mar 9 at 11:33
• Technically, it doesn't matter. Just check the formula of formation energy, we often use the eV/atom as the unit. – Jack Mar 9 at 11:37