An Isotropic Empirical Intermolecular Potential for Solid H_2 and D_2: A Classical Molecular Calculation

We develop an isotropic empirical potential for molecular hydrogen（H_2） and deuterium（D_2） by fitting to solidstate data, which is appropriate for classical molecular dynamics（CMD） approach. Based on the prior isotropic intermolecular potential used in self-consistent phonon approximation, a zero-point energy term and an embedded energy term are introduced to describe the H_2-H_2 and D_2-D_2 interactions in CMD simulations. The structure,cohesive energy and elastic properties of solid H_2（D_2） are used as the fitting database. The present method is tested by calculating the melting point of solid H_2, and the pressure and bulk elastic modulus as a function of volume. The developed potentials well reproduce many properties of solid H_2 and D_2.

An ab initio Study of Intermolecular Potential for Ne-HBr Complex

The potential energy surface of the ground state of the Ne-HBr complex has been calculated at several levels of theory, including the single and double excitation coupled cluster method with noniterative perturbation treatment of triple excitation CCSD(T). Calculations have been performed using the augmented correlation consistent polarized quadruple zeta basis set (aug cc pVQZ). Using the complete basis set (CBS), the global minimum with a well depth of approximate 70 516 cm -1 has been found for the linear Ne-Br-H structure ( θ =180 0°) with the distance between the Ne atom and the center of mass of the HF molecule equals (0 351 nm). In addition to the global minimum, there is a secondary minimum at R m=0 410 nm and θ =0° (a well depth of 57 898 cm -1 ). At last, the effects of the basis sets, H-Br bond length and theoretical methods on the intermolecular potential calculations of such weakly bound van der Waals complexes were discussed.

Determination of Transport Properties of Dilute Binary Mixtures Containing Carbon Dioxide through Isotropic Pair Potential Energies

The present work is concerned with extracting information about intermolecular potential energies of binary mixtures of CO2 with C2H6, C3H8, n-C4Hlo and iso-C4Hlo, by the usage of the inversion method, and then predicting the dilute gas transport properties of the mixtures. Using the inverted pair potential energies, the Chap- man-Enskog version of the kinetic theory was applied to calculate transport properties, except thermal conductivity of mixtures. The calculation of thermal conductivity through the methods of Schreiber et al. and Uribe et al. was discussed. Calculations were performed over a wide temperature range and equimolar composition. Rather accurate correlations for the viscosity coefficients of the mixtures in the temperature range were reproduced from the pre- sent unlike intermolecular potential energies. Our estimated accuracies for the viscosity are within ±2%. Acceptable agreement between the predicted values of the viscosity and thermal conductivity with the literature values demon- strates the predictive power of the inversion scheme. In the case of thermal conductivity our results are in favor of the preference of Uribe et al.＇s method over Schreiber et al.＇s scheme.

Muscle‘s Motion in an Overdamped Regime

Based on the stochastic inclined rods model proposed by H. Matsuura et al., we study the motion of actin myosin system in an overdamped regime. Our model is composed ofan inclined spring (rod), a myosin head and a myosin filament. The results of calculation show that the modelcan convert the random motion to one-directional motion, and the myosin head works as a resonator of random noise, which absorbs the energy through a stochastic resonance. The results show that the inclined rod and the intermolecular potential are very important for the system to move.