Accurate Enthalpy at a Specific Pressure

[Vahid Askarpour]

Dear VASP Users,

I have followed the following three steps outlined in the VASP manual for accurate energies (vasp5.3.2):

Relax from starting structure (ISMEAR should be 0 or 1).
Start a second relaxation from previous CONTCAR file (re-relaxation).
As a final step perform one more energy calculation with the tetrahedron method switched on (i.e. ISMEAR=-5), to get very accurate and unambiguous energies (no relaxation for the final run). The final calculation should be done with PREC=High, to get very accurate energies.

At the end of the second relaxation, I have the following in my OUTCAR:

external pressure=p1 (usually less than 1kbar)
Pullay stress=PSTRESS (set in the INCAR)
I also have the converged enthalpy.

Now when doing the third step,i.e., the self-consistent run, how do I get the enthalpy at PSTRESS? Should I set PSTRESS in the INCAR of the third step? Or should I use PSTRESS+p1 instead of PSTRESS? In other words, does p1 play any role in the self-consistent run to get accurate enthalpy at PSTRESS?

Thanks,

Vahid

[Vahid Askarpour]

It seems that no one uses VASP for calculating enthalpy at high pressure! Any comment from the admin would be appreciated.

Vahid