Extended Usage Request: Adding GROMACS angle function 10 - Restriced Bending Angle Potential

[mikeboyle321]

Hello again,

I'm using your program and it is awesome!

I do have one suggestion, that I think may help many CG users. That is adding the restricted bending angle potential (gromacs function 10) to the options for angular potential optimization. The restricted bending angle potential stabilizes systems and prevents them from blowing up in certain cases, especially when the CG model includes a dihedral angle. The reasoning behind the stabilization is illustrated in this exchange on the martini forum, where adding the restricted bending angle was needed to prevent my system from blowing up from lincs errors related co-linear atoms within the dihedral that caused the potential to diverge.

http://www.cgmartini.nl/index.php/component/kunena/15-water/5894-yet-another-thread-about-lincs-warnings-in-polarized-martini-water#8632

Cheers!
Mike

[CharlyEmpereurmot]

Dear Mike,

Thank you for your kind words!

We have been a bit busy recently, but we will get back to this. In the very first version my thoughts were that if the force constants are all tuned together, then this reduces the clashes between angles and dihedrals, therefore reducing the need to use the restricted bending angle potential. But I guess it is still useful/crucial in some cases, especially for the one you describe.

We will give it a try in the hopefully-soon future.
Thank you for your feedback!