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Restarting QCG

A guide on how to restart QCG calculations.

Restarting QCG calculations

QCG has a restart functionality. If, for example, a grow directory is present from a previous QCG calculation, it will be read automatically. If the solute and solvent geometry, as well as the number of solvent molecules to add, match the cluster found in the directory, QCG will skip the grow algorithm and start with the ensemble search.

As an example, we again use benzoic acid from the QCG Example 2 and add 30 water molecules with QCG. This is done by

crest --qcg --nsolv 30 --T 12 --alpb water

The resulting cluster looks good and we decide to generate an ensemble out of it. Using just the normal CREST NCI-MTD would yield a non-physical structure as the inner wall potential is missing. The hydrophilic moiety of the solute would thus move to the outer wall. Hence, we need to re-activate QCG. To do so, we have just to go into the directory we called QCG the last time and execute

crest --qcg --nsolv 30 --T 12 --alpb water --ensemble

QCG will read the cluster in the grow directory and start directly with the ensemble generation. After this, we can restart the calculation of solvation free energies with

crest --qcg --nsolv 30 --T 12 --alpb water --gsolv

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Copyright © 2022 Philipp Pracht.

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