Molcas Forum

gruszeck

Member

Registered: 2025-05-30

Posts: 1

Difficulty with QM/MM optimization

I am attempting to model a large system of a flavin in water, where the flavin undergoes QM geometric optimization and the water enviornment is relatively static and modelled at the MM level. It is giving an error related to the count. qmmm.i and Molcas.fh were both increased appropriately to allow for large system sizes

molcasAnion10A.Tinker.log

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 ###            TINKER  ---  Software Tools for Molecular Design            ###
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 ##                        Version 6.3  April 2015                           ##
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 ##               Copyright (c)  Jay William Ponder  1990-2014               ##
 ###                           All Rights Reserved                          ###
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 QMMM-QMMM-QMMM-QMMM-QMMM-QMMM-QMMM-QMMM-QMMM-QMMM-QMMM
 QMMM                                              QMMM
 QMMM           Modifications (2014) by:           QMMM
 QMMM    Nicolas Ferre, Aix-Marseille Universite   QMMM
 QMMM    Federico Melaccio, Universita di Siena    QMMM
 QMMM                                              QMMM
 QMMM-QMMM-QMMM-QMMM-QMMM-QMMM-QMMM-QMMM-QMMM-QMMM-QMMM

 This is a QM/MM calculation

 QMMMSETUP -- Wrong NbInQM value **

 TINKER is Unable to Continue; Terminating the Current Calculation

molcasAnion10A.key

* Change $PATH_TO_TINKER
parameters /usr3/graduate/gruszeck/OpenMolcas/tinker/params/charmm22cmap.prm
QMMM 17296
QM -1 31
MM -32 17296
* Add the atom type for the LA
atom             9999   51  O    "TIP3P Water O"     8     15.995     2
atom             9998  41  H    "TIP3P Water H"     1      1.008     1

vdw              9999            0.063013122    0.003041452
vdw              9998                  0.000       0.0000

charge           9999                 -0.01668
charge           9998                  0.00834

the first 31 atoms compromise the QM region flavin and the remaining are the water molecules. I am using OpenMolcas v23.02 I believe.

I was able to run the example from the manual fine so am unsure what the issue here is.

Any help is greatly appreciated.

Last edited by gruszeck (2025-05-30 00:27:56)