Molcas Forum

Addiw7

Member

Registered: 2016-05-24

Posts: 11

Constraining the internal coordinates so it is equal to another one

Dear Molcas Users,

I would like to do following thing in my system. Let's say there are three valence angles

a1 = X22 N6 C2
a2 = X22 N6 H16
a3 = X22 N6 H18

Now I don't really want to fix or constrain these but I want to keep them equal to each other, i.e.
a1 = a2 = a3

How can I do it with Molcas? I've read manual on SlapAf but I can't figure that out based on what is explained there.

Ignacio

Administrator

From: Uppsala

Registered: 2015-11-03

Posts: 1,203

Re: Constraining the internal coordinates so it is equal to another one

Something like:

Constraints
  a1 = X22 N6 C2
  a2 = X22 N6 H16
  a3 = X22 N6 H18
Value
  1.0 a1 + -1.0 a2 = 0.0
  1.0 a2 + -1.0 a3 = 0.0
End of constraints

Addiw7

Member

Registered: 2016-05-24

Posts: 11

Re: Constraining the internal coordinates so it is equal to another one

Thank you for helping me out with this!