CCL: PES scan of biphenyl

In order to have the entire phenyl group rotating around the C-C bond you have to leave a blank line after the internal coordinates and then type the following lines:

* #C1 #C2 *
#C0 #C1 #C2 #C3
and then another blank line. #Ci reffers to the numbers of the C atoms in your internal coordinate system. The first line is defining all the dihedral angles around the C-C bond in the bridge, and the second is just one of them, all the remaining ones will respond according to this one.
Hope this might help
Best regards
Joaquin Barroso-Flores
PS you are using opt=modredundant, aren't you?

"Xu Wang xwang6 ." <owner-chemistry]*[> escribió:
Sent to CCL by: "Xu Wang" []
I have a question about the potential energy surface scan for biphenyl (C12H10) about the dihedral angle between the two phenyl rings. The purpose of this calculation is to find out the rotational barrier of two phenyl rings. However, it seems that instead of twisting the entire phenyl group, only a single carbon and hydrogen atom move as I do the scan. I know some researchers have done this kind of work before. I wonder if anyone of you knows how to work this out. PS, I was using Gaussview 3.09 to build up the input file. Thanks!

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