In this paper we discuss the development, validation, and application of analytic potential energy functions for simulating Al nanoparticles. We consider six functions, the Ercolessi-Adams, Mei– Davenport, Sutton–Chen, and Streitz–Mintmire functions from the literature and the NP-A and NP-B functions from our group. We find that the NP-A and NP-B potential energy functions, which were fit to a ...

Using the core-mass approach, we have generated a vibrational-mass surface for the triatomic H3+. The coordinate-dependent masses account for the off-resonance nonadiabatic coupling and permit a very accurate determination of the rovibrational states using a single potential energy surface. The new, high-precision measurements of 12 rovibrational transitions in the ν2 bending fundamental of H3+...

Atomic oscillations present in classical molecular dynamics restrict the step size that can be used. Multiple time stepping schemes offer only modest improvements, and implicit integrators are costly and inaccurate. The best approach may be to actually remove the highest frequency oscillations by constraining bond lengths and bond angles, thus permitting perhaps a 4-fold increase in the step si...

This paper investigates the buckling of finite isotropic rectangular plates with circular cutout under uniaxial and biaxial loading. The complex potential method is used to calculate the pre-buckling stress distribution around the cutout in the plate with finite dimensions. To satisfy the in-plane boundary conditions, the generalized complex-potential functions are introduced and a new method b...

interaction of meso — tetrakis (p-sulphonato phenyl) porphyrin (hereafter abbreviated to tspp)with na+ has been examined using hf level of theory with 6-31g* basis set. counterpoise (cp)correction has been used to show the extent of the basis set superposition error (bsse) on thepotential energy curves. the numbers of na+ have a significant effect on the calculated potentialenergy curve (includ...

Highly accurate potential energy functions for the HeI and HeBr molecules have been calculated using an ab initio treatment that included basis set extrapolation to the complete basis set, as well as spin-orbit coupling in the ground 2sigma+ and first 2pi excited doublet states. The rovibronic bound state energies and resonance lifetimes were also evaluated by a Prony analysis of the autocorrel...

We investigate the jump motion among potential energy minima of a Lennard-Jones model glass former by extensive computer simulation. From the time series of minima energies, it becomes clear that the energy landscape is organized in superstructures called metabasins. We show that diffusion can be pictured as a random walk among metabasins, and that the whole temperature dependence resides in th...

We show that the motion of a slightly compressible fluid is near that of an incompressible fluid. That is, for a given initial velocity field, the motion of a compressible fluid with large sound speed is near to that of an idealized incompressible fluid. We consider the compressible fluid motion in Lagrangian coordinates and show that it can be defined by two functions giving the kinetic and po...

Molecular motors convert chemical energy into mechanical force and movement. Operating at energies just above those of the thermal bath, these motors experience large fluctuations, and their physical description must be necessarily stochastic. Here, motor operation is described as a biased diffusion on a potential energy surface defined by the interactions of the motor with its track and its fu...