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Faster way to calculate isotopic vibration frequencies?
Posted: Thu Jan 05, 2012 7:53 pm
by tanggara
Hi, is there any other way to calculate isotopic vibration frequencies other than changing the POMASS in the POTCAR? I'm using IBRION=5, POTIM=0.01, NSW=1, NFREE=2, and ISIF=2 in the INCAR.
Faster way to calculate isotopic vibration frequencies?
Posted: Fri Jan 06, 2012 11:45 am
by alex
Hi!
Are you talking about changing e.g. H to D and observing the change in the wavenumbers of some modes?
Cheers,
alex
Faster way to calculate isotopic vibration frequencies?
Posted: Mon Jan 09, 2012 11:01 pm
by tanggara
Hi Alex,
Thank you for responding. That is right, I'd like to see the shift of the wavenumber e.g. H to D of some modes.
Faster way to calculate isotopic vibration frequencies?
Posted: Tue Jan 10, 2012 10:02 am
by alex
Hi,
the fast answer is 'yes', it's possible: you have to use the Hessian out of OUTCAR and manipulate it accordingly (-> textbook).
Cheers,
alex
Faster way to calculate isotopic vibration frequencies?
Posted: Tue Jan 10, 2012 5:38 pm
by tanggara
Hi Alex,
Thank you for the answer! I am aware that grabbing the Hessian and manipulating it will result in being able to calculate the change in wavenumber on isotopic shift. Yet, I was curious to know whether there is a flag where VASP (or a script that) can do this manipulation accordingly. If not, the manual calculation is the way to go then. Thank you again Alex for the helpful information!