The parametrization and testing of the OPLS all-atom force field for organic molecules and peptides are described. Parameters for both torsional and nonbonded energetics have been derived, while the bond stretching and angle bending parameters have been adopted mostly from the AMBER all-atom force field. The torsional parameters were determined by fitting to rotational energy profiles obtained from ab initio molecular orbital calculations at the RHF/6-31G*//RHF/6-31G* level for more than 50 organic molecules and ions. The quality of the fits was high with average errors for conformational energies of less than 0.2 kcal/mol. The force-field results for molecular structures are also demonstrated to closely match the ab initio predictions. The nonbonded parameters were developed in conjunction with Monte Carlo statistical mechanics simulations by computing thermodynamic and structural properties for 34 pure organic liquids including alkanes, alkenes, alcohols, ethers, acetals, thiols, sulfides, disulfides, a...

https://sakai.rutgers.edu/access/content/user/kparis/biomaps_513_references/02_B_01_JACS118_11225_OPLS.pdf

Development and Testing of the OPLS All-Atom Force Field on Conformational Energetics and Properties of Organic Liquids

Apparent molal volumes and compressibilities are reported for dilute aqueous solutions of cyclic ethers, simple carbohydrates, and related polyhydroxy compounds. The results for carbohydrates are considered in the light of two theoretical descriptions of such systems, i.e., the semiideal solution approach of Stokes and Robinson, and the McMillan-Mayer theory ty[e of approach as employed by Kozak, Knight, and Kauzmann. It is concluded that neither model is satisfactory, and that for these solutions a specific hydration model, described in more detail in another paper, is more satisfactory.

Thermodynamic studies of dilute aqueous solutions of cyclic ethers and simple carbohydrates

Partial molar volumes and viscosity B-coefficients of arginine in aqueous glucose, sucrose and l-ascorbic acid solutions at T = 298.15 K

Intermolecular potential functions have been developed for use in computer simulations of alkyl ethers. The simple OPLS model was adopted and parameterized to yield good descriptions of bimolecular and ion-molecule complexes as well as to reproduce experimental thermodynamic properties of liquid ethers. The principal testing featured Monte Carlo statistical mechanics simulations for liquid dimethyl ether (DME), ethyl methyl ether (EME), diethyl ether (DEE), and tetrahydrofuran (THF). Average errors of 1–3% are obtained for the computed densities and heats of vaporization including results for THF at pressures up to 5000 atm. The torsional motion about the central CO bonds in EME and DEE was included in the simulations using rotational potential functions fit to results of molecular mechanics (MM2) calculations. The liquid-state environment is found to have negligible effect on the conformational equilibria.

Monte Carlo simulations of liquid alkyl ethers with OPLS potential functions

Interactions of some amino acids and glycine peptides with aqueous sodium dodecyl sulfate and cetyltrimethylammonium bromide at T=298.15 K: a volumetric approach

Heats of mixing and densities of very dilute aqueous solutions (mol) fraction concentration < 2 × 10–3 of cyclic ether derivatives have been measured at several temperatures. The solutions studied included tetrahydrofuran, tetrahydropyran, 1,4-dioxan, tetrahydrofurfuryl alcohol, and tetrahydropyran-2-carbinol. Limiting partial heats, heat capacities, volumes and expansibilities are discussed in terms of current ideas on polar and apolar hydration.

B. Watson

Papers

Calorimetric and volumetric studies of dilute aqueous solutions of cyclic ether derivatives