[Question from NMRWiki Q&A forum] shake routine and ncon parameter

[nmrlearner]

shake routine and ncon parameter

Trying to do molecular dynamics with explicit water molecules I came across a problem with SHAKE routine:

shake reference = parameters bonds (hydrogen) (all) tolerance = 1.0e-06 nconstraints=8000end

and error message after this is:

X-PLOR>shake SHAKE> reference = parameters SHAKE> bonds (hydrogen) (all) SELRPN: 7142 atoms have been selected out of 11032 SELRPN: 11032 atoms have been selected out of 11032 SHKSET: reference = parameters %XREFIN-ERR: allocation for SHAKE-constraints exceeded increase NCON parameter and run again %XREFIN>-ERR: exceeded allocation for SHAKE-constraints %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%% BOMLEV= 0 reached. Program execution will be terminated. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%% Subroutine DIE called . Terminating

Supposedly, I have 7142 hydrogen atoms and only constraints which SHAKE routine will take into consideration is bonds between hydrogen and heavy atoms, no more then 7142 . So, nconstraits = 8000 should work. I tried 8000, 30000, 600000... Still the same error message.Sours code didn't give me any limitation for this parameter, it should be integer, it is not limited in value. What is wrong with it?Can somebody give me any advise? Thank you all.



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