The location of energy minima on the conformational energy surface
of molecules by computational methods
(conformational searching) continues to play a key role in
computer-assisted molecular modeling. Although a
number
of conformational search procedures have been devised over the past
several years, new more efficient methods are
urgently needed if molecules with increased complexity are to be
treated in a quantitative manner. In this paper we
describe a method, termed low-mode search (LMOD), which is based on
eigenvector following (or mode following),
for the exhaustive exploration of the potential energy hypersurface of
molecules. It is particularly efficient at searching
the conformational space of both cyclic and acyclic molecules, and we
describe its effectiveness for a number of
conformational search problems including acyclic, monocyclic, and
bicyclic hydrocarbons and cyclic pentapeptides.
No special treatment of rings in cyclic molecules is necessary,
nor is it necessary to define rotatable bonds. LMOD
generates structures “automatically” with minimum input from the
user. We demonstrate that LMOD is one of the
most efficient procedures yet devised for conformational searching of
small- to medium-sized molecules.