[gmx-users] On CHARMM angle bending potential

[Mr Bernard Ramos]

Hi all!

The potential for the angle-vibration potential in CHARMM is V = k(a - a0)^2. Its corresponding force field is proportional to 1/sin(a) which blows up when a approaches \pi or when the molecule is in linear arrangement. I am wondering how Gromacs calculates the angle-bending potential of a linear molecule such as carbon dioxide when it the force vector is singular at a equal to \pi?

Thank you.

Bernard