[gmx-users] QM-MM Minimization

[Jose Tusell]

Dear Gromacs users,

I've been carrying out QMMM minimizations using gromacs and orca over the
past year.  I found that the number of point charges that are included in
the *.pc file significantly affect the energy of QM subsystem.  Throughout
a minimization the number of point charges included in this file increased
by 18.  I noticed that almost every time a new charge is added or
eliminated from this file the QM energy changes.  Since the QM energy of my
subsystem is as large as the MM energy this causes the overall potential to
shift.  I was wondering if anyone had some insight into how to main the
number of point charges constant throughout this process.

Thanks in advance,

Jose Tusell