OPLS Force Field Research Articles

Molecular simulation of multicomponent reaction and phase equilibria in MTBE ternary system

AbstractReaction and phase equilibria in the isobutene + methanol + MTBE ternary system were studied using the reaction‐ensemble Monte Carlo (REMC) simulation method. The system was modeled at the molecular level by an OPLS force field. No adjustable binary cross‐interaction parameters or mixture data of any kind were used in the simulation model, and only vapor‐pressure data for the pure components was required as input. The REMC method also computes excess internal energies and molar volumes as a biproduct of the simulations. Both the nonreacting and reacting ternary systems were considered over the temperature range of practical interest at 5 bar. Results are compared with the calculations using two conventional thermodynamic approaches: the Wilson and UNIFAC free‐energy models for the liquid phase, together with a truncated virial equation of state for the gas phase in both cases. Computer simulation results were similar to those of the thermodynamic approaches, and they are arguably more accurate.

Generation of OPLS-like charges from molecular electrostatic potential using restraints

A new method for generating atom-centered charges for use in condensed phase computer simulations is presented, which is based on a restrained electrostatic potential (RESP) procedure. Charges are calculated from a least-squares fit to the quantum mechanical electrostatic potential with a restraint applied to reduce their magnitude. The restraint developed here offers advantages over that used in RESP. The magnitude of the restraint is optimized to yield charges as close to the equivalent OPLS values as possible while still reproducing the molecule's electrostatic potential. A cross-validation analysis is used to show that the restraint is insensitive to the selection of OPLS molecules from which it is derived. Thus, with this method, OPLS-like charges may be produced from the electrostatic potential for atom types not in the OPLS force field. In addition, the restraint is shown to reduce the conformational dependence of the charges. ©1999 John Wiley & Sons, Inc. J Comput Chem 20: 483–498, 1999

Molecular Dynamics of RNA with the OPLS Force Field. Aqueous Simulation of a Hairpin Containing a Tetranucleotide Loop

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMolecular Dynamics of RNA with the OPLS Force Field. Aqueous Simulation of a Hairpin Containing a Tetranucleotide LoopDominic A. ZichiCite this: J. Am. Chem. Soc. 1995, 117, 11, 2957–2969Publication Date (Print):March 1, 1995Publication History Published online1 May 2002Published inissue 1 March 1995https://doi.org/10.1021/ja00116a001RIGHTS & PERMISSIONSArticle Views220Altmetric-Citations46LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (8 MB) Get e-Alerts Get e-Alerts