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                        QCG final geometry optimization at GFN-FF
Hi everyone, I'm conducting Solvation Free Energy calculations using QCG for several macromolecules in 100 solvent molecules. I'm curious if it's feasible to employ the GFN-FF method for the Final Geometry Optimization. The default method is GFN2-xTB, which appears to be quite costly for my systems. Here's my command line for the calculations: crest mol_1.xyz --qcg water.xyz --nsolv 100 --gfnff --T 60 --gsolv --nclus 5 --mreset 4 --alpb water --nofix
I'm using CREST version 2.12.
Thanks, Mostafa
Hi Mostafa, after CREST version 2.12, I updated the source code so that the GFN2-xTB optimization was made optionally if a different method should be used and is then only be performed when using the "--fin_opt_gfn2" flag. This feature is currently only available in the Continous release version or an other version compiled with the current source code.
Thank you for your reply. If I want to do everything at the GFN-FF level, do I also need to specify the "--enslvl gfnff" keyword: crest mol_1.xyz --qcg water.xyz --nsolv 100 --gfnff --enslvl gfnff --T 60 --gsolv --nclus 5 --mreset 4 --alpb water --nofix
I just ran the calculations with the Continous release version (precompiled binaries) using the following command line and it crashed in the "Multilevel Ensemble Optimization" step with this error:
crest pentanol.xyz --qcg benzene.coord --nsolv 25 --gfnff --T 120 --gsolv --nclus 4 --fscal 0.65 --gbsa benzene
input  file name : crest_rotamers_0.xyz
output file name : crest_rotamers_1.xyz
reference state Etot :  -62.1430257400000
forrtl: severe (174): SIGSEGV, segmentation fault occurred
Image              PC                Routine            Line        Source
crest              0000000002659710  Unknown               Unknown  Unknown
crest              00000000006E1484  cregen_conffile         2510  cregen.f90
crest              00000000006C01EC  newcregen_                260  cregen.f90
crest              00000000005AE3A4  confg_chk3_               913  confscript2_misc.f90
crest              00000000005AE1C8  sort_and_check_          1052  confscript2_misc.f90
crest              0000000000517B0D  crest_multilevel_         396  search_conformers.f90
crest              0000000000512C61  crest_search_imtd         129  search_conformers.f90
crest              00000000004214E5  qcg_ensemble_            1029  solvtool.f90
crest              0000000000406350  crest_solvtool_           102  solvtool.f90
crest              00000000004041F8  MAIN__                    262  crest_main.f90
crest              000000000040336D  Unknown               Unknown  Unknown
crest              000000000265B9E0  Unknown               Unknown  Unknown
crest              000000000040324E  Unknown               Unknown  Unknown_
To apply GFN-FF in every step, both the --gfnff and --enslvl gfnff options need to be used. Thank you for reporting the bug. There have been some bug fixes recently that should also address this issue.
Thank you for the updates.