Hi,

I am creating a Force Field (FF) using the FF editor in Materials Studio.

However when I try to define the vdw it only allows me to set the OFF_DIAGONAL_VDW contributions.

If I open the .off file with a text editor I see that the values for the DIAGONAL_VDW.

My questions are:

the right to way to set the values is to open the .off file and assign the values to the

DIAGONAL_VDW to each atom type and the OFF_DIAGONAL_VDW are calculated based on the combination rule (e.g. geometric)?

When should I put OFF_DIAGONAL_VDW values in the FF editor interactions?

Regarding the X atom type, in Dreiding FF for instance some interactions have the X atom type.

What does this mean?

Best,

Simão