Cell size in GEO OPT for a cluster or molecule

[Niharendu Choudhury]

Dear all,

Greetings to all from Mumbai, India.

What should be the cell size relative to cluster/molecule size

when GEO OPT is carried out using CP2K. Any thumb rule?

Niharendu Choudhury

[Matt Watkins]

You want to have all the electron density decaying to ~0 around the molecule before it repeats, normally requires about 5A of space beyond the atom position. You want the cell to be large enough that there are no major electrostatic interactions between images. 15A^3 is normally quite sufficient - bigger if your molecule is bigger.

You can also run non-periodically using psolver wavelet and periodic none n the poisson section and periodic none in you cell section.

Matt

[Niharendu Choudhury]

Dear Dr. Watkins,

Thanks for your advice. Is there any standard input file available?

Regards

N Choudhury

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Dr. Niharendu Choudhury

Scientific Officer

Theoretical Chemistry Section

Chemistry Group

Bhabha Atomic Research Centre

Mumbai- 400 085, India.

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