

AMBER Archive (2006)Subject: AMBER: Curve fitting during dihedral parameter calculation From: Prashanth Athri (athriprashanth_at_yahoo.com)Date: Thu Oct 19 2006  14:15:21 CDT
Dear Users:
I wanted to know if there is a 'recomended procedure', and a reference for the same, to fit a Quantum derived energies to the fourier cosine that Amber uses to model torsion potentials.
As in once we have a list of energies for the torsion 'theta' about the dihedral ZZZAZSZD, for 0 to 360 in, say, 10 degree intervals to get the V1, V2, etc we fit this curve to Ptot:
Ptot(theta)= P2(theta) + P6(theta)
where,
P2(theta) = V2/2 (1+ cos(2*thetaphase))
P6(theta) = V6/2(1+ cos(6*thetaphase))
and more terms, if needed. [P1,P3,P4]
So, my question is whats the best curve fitting protocol to do this. Is there an algorithm? Does someone have a pseudocode for the same?
Thanks in advance.
Regards,
Prashanth
 
