Author Topic: Determine correction to Gibbs free energy  (Read 5550 times)

hechinger

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Determine correction to Gibbs free energy
« on: October 06, 2011, 04:47:28 PM »
Hello everybody,

I am looking for a way to compute the correction to the thermal correction to Gibbs free energy (as computed in a Gaussian frequency calculation). To this end, I called "aofroce" after optimizing the geometry geometry (RI-BP / TZVP) and then the "freeh" module. However "aoforce" turned out to be quiet time consuming. I am not sure what exactly "aoforce" calculates, and finally I am only interested in the correction to the thermal correction to Gibbs free energy. Therefore I was wondering if there is exists a more efficient way (parameter-set) for "aoforce" or "NumForce" to only perform the required calculations for enabling "freeh" to compute the energy correction.

Any hint is greatly appreciated, and thanks for your advise in advance!

Best regards,

Manuel

antti_karttunen

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Re: Determine correction to Gibbs free energy
« Reply #1 on: October 06, 2011, 07:36:36 PM »
Hi,

Calculating the harmonic vibrational frequencies with aoforce/NumForce is indeed quite time-consuming, but there is really no way to avoid it if you want to obtain Gibbs free energies. In the latest version you can run aoforce in parallel  on multi-core machines and this will speed up the calculations nicely, if you have computational resources available.

Best wishes,
Antti