Pressure Annealing as a Complement to Temperature Annealing To Find Low-Energy Structures of Oligomeric Molecules

• Published in: Journal of chemical theory and computation 2009-07, Vol.5 (7), p.1883-1894
• Main Authors: Hixson, Christopher Adam, Wheeler, Ralph A
• Format: Article
• Language: English
• Subjects: Polymers
• ISSN: 1549-9618; 1549-9626
• DOI: 10.1021/ct800451c

Finding the lowest-energy geometry of a molecule or collection of molecules is a fundamental challenge of modern computational chemistry and is closely related to the more general problem of optimizing a function. Temperature annealing, popularly called simulated annealing, is a powerful and commonly used technique, but it is not well suited to conformational sampling of long, oligomeric molecules. A method is presented herein that incorporates pressure as an optimization parameter to complement temperature annealing, and several tests of its effectiveness are described. Bayesian statistical analysis shows that pressure−temperature annealing confers no advantage in control simulations of Lennard-Jones particles, but it yields lower-energy structures than pure temperature annealing with significant credibility for two model polyethers, monoglyme (CH3OCH2CH2OCH3) and tetraglyme [CH3(OCH2CH2)4OCH3].