From: Daniel Fellner (
Date: Sun Mar 21 2021 - 06:28:55 CDT

Hi all,

I'm optimising a set of dihedrals for a strained alkane. It's a
2,2,3,3-tetramethyl substituted cyclopropane, and one of the high penalty
dihedrals is Me-2-3-Me.

What I'm unsure of is which methyl group/s to set for the dihedral scan for
this term: Trans or cis to the first methyl? The start angles are ~0 and
~140 degrees respectively, and I doubt that a +/- 180 degree scan would run
smoothly. Should I scan both to +/- 90 degrees and use both to construct
the PES?

My other concern is that the methyls are quite close to each other so they
would interfere sterically no matter what I choose. But they obviously
can't be removed as they're part of the dihedral definition.

*Daniel Fellner BSc(Hons)*
PhD Candidate
School of Chemical Sciences
University of Auckland
Ph +64211605326