Confusion on the order of calculations.

[pranjal222]

Dear Community,

I would like to ask a very basic question. In the following INCAR file parameters, the LOPTICS will be calculated on the final relaxed structure or on the initial structure I had provided in my POSCAR?

ISTART = 0
ICHARG = 2
INIWAV = 1
ENCUT = 500.00 eV
PREC = Normal
LREAL = Auto
ISMEAR = 0
SIGMA = 0.01
EDIFF = 1.0E-5
NELM = 200
GGA = PE
NCORE = 04
NBANDS = 260
NEDOS = 2000
ADDGRID = .TRUE.

##Relaxation
NSW = 200
EDIFFG = -1.0E-4
IBRION = 1
POTIM = 0.5
ISIF = 3
ADDGRID = .TRUE.

LOPTICS =.TRUE.

Kindly let me know so that I do not repeat the same things again and again. Right now, I am doing the relaxation first and then renaming the CONTCAR to POSCAR and just calculating the LOPTICS. But I think I dont need to do it as it can be done in one calculation. Requesting you to kindly confirm the same.

Thank you.

Regards,
Pranjal

[fabien_tran1]

The optical properties are calculated at the final structure. This is something that you could have deduced yourself by comparing the plasma frequency obtained from the two static calculations at the initial and final structures to the value obtained with the INCAR that does everything (relaxation+optics).