Glenn Torrie

Bio: Glenn Torrie is an academic researcher from University of Toronto. The author has contributed to research in topics: Dynamic Monte Carlo method & Monte Carlo method. The author has an hindex of 4, co-authored 4 publications receiving 1280 citations.

Heat capacity of the restricted primitive model near criticality

Abstract: This concerns the supercritical heat capacity of the “restricted primitive model” of Coulombic systems, one aspect of a more general attempt to study the phase transition and critical behavior of this model using thermodynamic-scaling Monte Carlo techniques. We see no indication of Ising-type divergence of the heat capacity; the strength of the evidence in this regard is discussed.

Further remarks on the heat capacity of the restricted primitive model

Abstract: This concerns the critical behavior of the restricted primitive model. Luijten, Fisher, and Panagiotopoulos [J. Chem. Phys. 114, 5468 (2001)] recently suggested that canonical heat capacity data previously published by us might be consistent with nonclassical behavior, which had appeared unlikely to us. Their argument turns on a supposed similarity of behavior of our results with results they have obtained for a lattice version of the model. We point out that the behaviors are in fact very dissimilar, however, and we explain why we do not find their suggestion plausible.

CHARMM: the biomolecular simulation program.

Abstract: CHARMM (Chemistry at HARvard Molecular Mechanics) is a highly versatile and widely used molecu- lar simulation program. It has been developed over the last three decades with a primary focus on molecules of bio- logical interest, including proteins, peptides, lipids, nucleic acids, carbohydrates, and small molecule ligands, as they occur in solution, crystals, and membrane environments. For the study of such systems, the program provides a large suite of computational tools that include numerous conformational and path sampling methods, free energy estima- tors, molecular minimization, dynamics, and analysis techniques, and model-building capabilities. The CHARMM program is applicable to problems involving a much broader class of many-particle systems. Calculations with CHARMM can be performed using a number of different energy functions and models, from mixed quantum mechanical-molecular mechanical force fields, to all-atom classical potential energy functions with explicit solvent and various boundary conditions, to implicit solvent and membrane models. The program has been ported to numer- ous platforms in both serial and parallel architectures. This article provides an overview of the program as it exists today with an emphasis on developments since the publication of the original CHARMM article in 1983.

The weighted histogram analysis method for free-energy calculations on biomolecules. I: The method

Abstract: The Weighted Histogram Analysis Method (WHAM), an extension of Ferrenberg and Swendsen's Multiple Histogram Technique, has been applied for the first time on complex biomolecular Hamiltonians. The method is presented here as an extension of the Umbrella Sampling method for free-energy and Potential of Mean Force calculations. This algorithm possesses the following advantages over methods that are currently employed: (1) It provides a built-in estimate of sampling errors thereby yielding objective estimates of the optimal location and length of additional simulations needed to achieve a desired level of precision; (2) it yields the “best” value of free energies by taking into account all the simulations so as to minimize the statistical errors; (3) in addition to optimizing the links between simulations, it also allows multiple overlaps of probability distributions for obtaining better estimates of the free-energy differences. By recasting the Ferrenberg–Swendsen Multiple Histogram equations in a form suitable for molecular mechanics type Hamiltonians, we have demonstrated the feasibility and robustness of this method by applying it to a test problem of the generation of the Potential of Mean Force profile of the pseudorotation phase angle of the sugar ring in deoxyadenosine. © 1992 by John Wiley & Sons, Inc.