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592. CONFLEX: Generation of Ring Conformers by Corner-
Flapping Algorithm
by Hitoshi Goto and Eiji Osawa, Department of
Chemistry, Faculty of Science, Hokkaido University,
Sapporo 060, Japan
CONFLEX systematically generates all conformers for a
flexible ring structure by the "corner-flapping"
algorithm.1 Four adjacent bonds on the ring are
rotated simultaneously in one corner-flap operation.
The central ring atom in these bonds is the "corner".
For a given initial structure, all the corners are
exhaustively flapped, while each conformation resulting
from flapping is geometry-optimized with MM2(87)2 as a
minimizer. In order to turn the MM2(87) program into a
minimizer routine, it is necessary to make a few
changes; the conformer that results from each
flapping/energy minimization cycle is tested for
redundancy by comparing the total steric energy and the
dihedral angle values along the ring with those of the
already saved conformers. The new conformer is saved
as the candidate for the initial structure. Total
computer time is approximately equal to nNt, where n is
the number of corner atoms on the ring, N is the number
of conformers, and t is the average time of energy-
minimization for a flapped conformation.
CONFLEX also generates all the rotamers of side chains,
conserves configuration of asymmetric atoms and
automatically removes redundancy due to symmetry. With
several provisions to increase computing speed, CONFLEX
is probably one of the fastest programs to cover the
torsional energy surface of cyclic molecules of medium
size.
What QCPE is delivering in this package is a main
program and a series of subroutines which will not
execute alone. In order to use this package you must
have or obtain the MM2(87) system. QCPE distributes
this system to academic institutions only. For such
institutions who do not now have MM2(87), it can be
ordered from QCPE. A signed use agreement must
accompany the order. Please call QCPE for details.
Nonacademic users will have to be prepared to adapt
this system to whatever minimizer they have.
CONFLEX will be distributed in ANSI D (VAX COPY) format
as multiple files.
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References:
1. H. Goto and E. Osawa, J. Am. Chem. Soc., 111,
8950-51 (1989).
2. N. L. Allinger, QCPE Bull., 9, 58 (1989).
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FORTRAN 77 (VAX)
Lines of Code: 3200
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