Hi,

Is there a method to define two distinct terms for the same atoms involved in an angle bending scenario? Specifically, consider the angle between O-Cu-O atoms. I would like to establish force field angle bending terms for both 120 degrees and 180 degrees, like so:

O Cu O 120deg
O Cu O 180deg

Unfortunately, achieving this directly within off force field files seems to be impossible (MS simply won't allow it). I'm exploring alternative approaches to accomplish this. One working solution I've implemented involves identifying which oxygen atoms are part of the 180-degree angle (O-Cu-O angle in this case is perpendicular to the CuO3 plane) and assigning a different force field type to them. While this approach works, it's not particularly elegant as it results in different force field types for essentially the same atoms. I'm curious if there's a more refined or efficient way to achieve this within off force field. Any insights would be greatly appreciated.

Best wishes,

Bojan