CONFORMATIONAL SEARCHING METHODS FOR SMALL MOLECULES .2. GENETIC ALGORITHM APPROACH

We demonstrate the use of a genetic algorithm (GA) search procedure for finding low-energy conformations of small to medium organic molecules (1-12 rotatable bonds). GAs are in a class of biologically motivated optimization methods that evolve a population of individuals where individuals who are more ''fit'' have a higher probability of surviving into subsequent generations. Here, an individual is a conformation of a given molecule and the fitness is the molecule's conformational energy. In the course of a simulated evolution, the population produces conformations having increasingly lower energy. We test the GA method on a suite of 72 molecules and compare the performance against the CSEARCH algorithm in Sybyl. For molecules with more than eight rotatable bonds, the GA method is more efficient computationally and as the number of rotatable bonds increases the relative efficiency of the GA method grows. The GA method also found energies equal to or lower than the energy of the relaxed crystal structure in the large majority of cases. (C) 1993 by John Wiley & Sons, Inc.