Calculate S_msRRHO

How to calculating an averaged S_msRRHO for CREST’s entropy mode.

Calculating an averaged S_msRRHO

In Chem. Sci., 2021, 12, 6551-6568 the conformational entropy is calculated as

\(S_\text{conf} = S'_\text{conf} + \bar{S}_\text{msRRHO}\)

where \(S'_\text{conf}\) is the conformational term proportional to the Gibbs-Shannon entropy, and the averaged S_msRRHO is obtained as

\(\bar{S}_\text{msRRHO} = \sum_i^\text{ensemble} p_i S_{\text{msRRHO},i} - S_{\text{msRRHO},0}\)

The averaged S_msRRHO is an ensemble average over all S_msRRHO contributions for each conformer. Note that the S_msRRHO entropy for the input structure, S_msRRHO,0 is substracted here in order to make the entire term S_conf an additive correction to the DFT-based molecular entropy.

The averaged S_msRRHO can be calculated in a standalone application of CREST, similar to the --mdopt and --screen commands. The respective calculation can be invoked by the --rrhoav command.

crest --rrhoav input-ensemble.xyz