Hi, I want to use python script to adjust the bond angle randomly and only accept the case if the random new angle is larger than old one. I use "mcopy" to recover the old angle if the new is smaller. But I encounter a problem: if I use "mcopy #old #new setting a" or "x" or "y", the after "adjust angle anglenew" command, the angle adjusted is not the anglenew, but a different one. I don't know why. I hope anyone can solve my problem.. Below is the python script and init.mol2. PYTHON SCRIPT: import os import time import chimera import random from chimera import runCommand as rc from chimera.tkgui import saveReplyLog import MoleculeTransform from MoleculeTransform import transform_atom_coordinates import numpy as np import sys import re #open initial conformation init.mol2 opened = chimera.openModels.open("init.mol2")# opened as model 0 in chimera chimera.openModels.open("init.mol2") # opened as model 1 in chimera, used to store old conformation in monte carlo simulation rho = opened[0] print "angleold anglenew angle_after_adjust" for pdbi in range(0,20): random_atom = 1 an0 = rho.atoms[random_atom-1] an1 = rho.atoms[random_atom] an2 = rho.atoms[random_atom+1] angleold = chimera.angle(an0.xformCoord(),an1.xformCoord(),an2.xformCoord()) anglenew = random.random()*180 rc("adjust angle %f %s %s %s"%(anglenew,an0.oslIdent(),an1.oslIdent(),an2.oslIdent())) angleafter = chimera.angle(an0.xformCoord(),an1.xformCoord(),an2.xformCoord()) print str(angleold)+" "+str(anglenew)+" "+str(angleafter) if anglenew>angleold: rc("mcopy #0 #1 settings x") else: rc("mcopy #1 #0 settings x") rc("close all") rc("stop now") INIT.MOL2: @<TRIPOS>MOLECULE init.mol2 3 2 3 0 0 NUCLEIC_ACID NO_CHARGES @<TRIPOS>ATOM 1 C 1.7324 -0.5083 0.8663 C.3 1 DA 0.0000 2 C -0.6180 0.4940 -0.0060 C.3 2 DA 0.0000 3 C 1.2450 0.9460 1.8950 C.3 3 DA 0.0000 @<TRIPOS>BOND 1 1 2 1 2 2 3 1 @<TRIPOS>SUBSTRUCTURE 1 DA 1 RESIDUE 4 A DA 1 ROOT 2 DA 2 RESIDUE 4 A DA 2 3 DA 3 RESIDUE 4 A DA 1