Calculating entropy and ZPE before and after adsorption

Vasp transition state theory tools

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lexa
Posts: 8
Joined: Mon Feb 07, 2011 6:14 pm

Calculating entropy and ZPE before and after adsorption

Post by lexa »

Hi,

I want to calculate the Gibbs free energy of a reaction where a molecule adsorbs to the surface.

I am wondering whether your scripts allows the calculation of the entropy and zero point energies of the adrobate before and after adsorption?

Thanks,
Alexandra
graeme
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Re: Calculating entropy and ZPE before and after adsorption

Post by graeme »

The scripts can be used to calculate the vibrational modes, zero point energies, and vibrational entropies. For the gas phase species, however, you will need to include the translational entropy, based upon the temperature and pressure, yourself.
lexa
Posts: 8
Joined: Mon Feb 07, 2011 6:14 pm

Re: Calculating entropy and ZPE before and after adsorption

Post by lexa »

Can you please tell me which script is used to obtain the vibrational entropy term? have used dymzpbar.pl to obtain the ZPE and that works.

Thanks
graeme
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Posts: 1999
Joined: Tue Apr 26, 2005 4:25 am
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Re: Calculating entropy and ZPE before and after adsorption

Post by graeme »

Ah, I think we just calculate the ratio of vibrational partition functions. For the entropy, you can take the set of vibrational frequencies and calculate:
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