Application of Newton-Raphson optimization techniques in molecular mechanics calculations

Applications of the Newton-Raphson optimization technique to molecular mechanics calculations are discussed. The theory for applying this method is developed in terms of the spectroscopic Wilson S vectors for stretching, bending and torsional internal coordinates. An exact method for calculating the geometries of transition states for interconversion processes is shown to follow directly from the use of Newton-Rapbson optimization. Also, a precise method is developed for calculating the detailed minimum energy pathway for interconversions. A computer program EMIN is described, and applications of this program to geometry optimization, normal coordinate analysis, thermodynamic calculations and synthesis of electron diffraction radial distribution curves are ilhktrated using the molecule cyclohexane.