Hello,

Currently I am working with a polymer and I want to geometrically optimize and anneal the polymer with Forcite and then run molecular dynamics on the polymer with Forcite on a remote computer cluster.  Right now 2 nanoseconds of annealing and 2 nanoseconds of molecular dynamics takes around 2 days even when I run the job in parallel with 8 processors.  The time step that I take is 1 femtosecond because any longer will usually cause the job to fail.  I thought that if I could eliminate Carbon - Hydrogen bond vibrations or constrain these bonds on the polymer then the calculation time could be cut down significantly and I could maybe even take larger time steps.  Is there any way to do this?  I am using Materials Studio 6.0 on windows 7.

PS  I have tried using motion groups to constrain the bond lengths during annealing, but this has not seemed to work.  After reading some other discussion forums it seems as though this will only work to constrain bonds during geometry optimization, but I am not completely sure about that.