Hi, I am new to chimera and I am attempting to write a python script that would rotate the models by some angle and then writing it to another pdb file with changed coordinates. import chimera import os from cStringIO import StringIO for filename in os.listdir("test_python"): print filename model = chimera.openModels.open('test_python/'+filename) mol = model[0] axis = chimera.Vector(1,1,1) angle = 180 xf = chimera.Xform.rotation(axis,angle) matrix = chimera.Xform.getOpenGLMatrix(xf) print mol.openState.xform mol.openState.localXform(xf) print mol.openState.xform mem =StringIO() chimera.pdbWrite(model,mol.openState.xform,mem) print mol.openState.xform with open('converted.pdb','w') as f: f.write(mem.getvalue()) This is my code so far. When I run it, the converted.pdb file does not contain any changed coordinates. The coordinates of the atoms are same as before. Am I making some mistake? Is there any other way of doing this easily? Thanks. Regards, Kavya Shankar