Hessian matrix calculation

[Lecuyern]

Hi everyone,

I am sorry to bring again the question of the Hessian matrix but the other posts did not totally answer my questions.

I need to make an Hessian matrix calculation for a system that include a membrane and an adsorbant.

I am totally new to setting manually the commands of VASP; I used to do it with the help of a graphic interface that unfortunately doesn't allow me to do this type of calculations.

So I would like to know exactly what are the VASP commands I need to include in the different input files in order to perform a correct Hessian Matrix calculation.

I saw in the other posts some commands like IBRION = 5 and NSW =1 (can it be more than one like 100?!) but what else is needed?

Could someone help me with this?

Thanks a lot

[admin]

if you have in mind to calculate vibrational spectra, please rather
1) converge the ionic configuration of your system completely
2) calculate the spectrum for the converged geometry, using NSW=1.
As these runs are very time consuming (please note that the number of degrees of freedom - unless specified via the 'selective dynamics' tag in POSCAR - is 3*N(atoms)), because each ionic displacement has to be converged electronically
The number of considered displacements is not related to the NSW parameter for IBRION=5, but set to the number of degrees of freedom.
3) please reduce POTIM (to about 0.015) to make sure that each displacement is within the harmonic limit.