CHARMM Development Project Forums User Discussion & Questions Energy terms, Constraints, Restraints, and Solvation Fix conformation while allowing diffusion in membrane

GROMACS has this function, however that software is designed for proteins. TurboMole has this function, but is not a biomolecular MD suite.

Lennart, that wasn't a very helpful remark. I am aware that the purpose of MD is to change the conformation... there are also times when you want to change only a portion of the conformation and keep another portion rigid.

rmv: I will try SHAPEs. I checked out that link you provided and am still figuring out the syntax for my needs. I have already tried CONS HARM BESTFIT and didn't get the desired effect.