A guide on how to restart 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.
--grow in a directory where an ensemble folder is placed, will cause it to be deleted.
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 benzoic_acid.xyz --qcg water.xyz --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 benzoic_acid.xyz --qcg water.xyz --nsolv 30 --T 12 --alpb water --ensemble
--nsolv are matching the data in the
grow directory. All other settings can be changed. Also, a solvation free energy computation can be done by substituting
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 benzoic_acid.xyz --qcg water.xyz --nsolv 30 --T 12 --alpb water --gsolv