CCL: Freezing angles in GAMESS-UK/CHARMM QM/MM simulations?

[Jens Thomas <j.m.h.thomas*dl.ac.uk>]

 Sent to CCL by: Jens Thomas [j.m.h.thomas .. dl.ac.uk]
 Dear James,
 It is possible to hold an angle or bond length constant in GAMESS-UK,
 provided that the molecule has been defined with a Z-matrix. If this is
 the case, then you can decide which of the bond lengths and angles are
 free to vary and those that are to be held constant.
 There is more information on this in the GAMESS-UK manual at:
 http://www.cfs.dl.ac.uk/docs/gamess_manual/chap3/node11.html
 If you don't have a Z-matrix definition for your molecule, than the
 freely available CCP1GUI has the ability to automatically construct a
 Z-matrix definition from Cartesian coordinates.
 You can find out more about the CCP1GUI at:
 http://www.cse.clrc.ac.uk/qcg/ccp1gui/index.shtml
 Whether this is possible for QM/MM modelling depends on the QM/MM
 environment within which you are using GAMESS-UK. If that permits the QM
 region to be defined with a Z-matrix, or supports constraining certain
 bonds and angles itself, there should be no problem in keeping the
 relevant bonds and angles fixed.
 I hope this helps.
 Best wishes,
 Jens
 James N Scott scottjn],[gmail.com wrote:
 > Sent to CCL by: "James N Scott" [scottjn-$-gmail.com]
 > Greetings CCLers.  I am on the verge of purchasing GAMESS-UK in order to do
 some simple QM/MM simulations of different small molecules in water, with the
 goal of examining solvent effects on spectra.
 >
 > Is it possible to make constant an angle or bond length internal to the QM
 system of interest?  For instance, can I fix a dihedral angle between two QM
 molecules embedded in MM water molecules, or a bond length within a single QM
 molecule?
 >
 > Thanks very much for any assistance!
 >
 > J. Nathan Scott>
 >
 >
 >
 >
 >