H. Bernhard Schlegel
Department of Chemistry, Wayne State University, Detroit, Michigan, 48202 USA
Geometry optimization is an important part of most quantum chemical calculations. This talk surveys methods for optimizing equilibrium geometries, locating transition structures, and following reaction paths. The emphasis is on optimizations using quasi-Newton methods that rely on energy gradients, and the discussion includes Hessian updating, line searches, trust radius, and rational function optimization techniques. Single-ended and double-ended methods are discussed for transition state searches. Single-ended techniques include quasi-Newton, reduced gradient following and eigenvector following methods. Double-ended methods include nudged elastic band, string, and growing string methods. The discussions conclude with methods for validating transition states and following steepest descent reaction paths.