We present pair potentials for fluorinated methanes and their dimers with CO(2) based on ab initio potential energy surfaces. These potentials reproduce the experimental second virial coefficients of the pure fluorinated methanes and their mixtures with CO(2) without adjustment. Ab initio calculations on trimers are used to model the effects of nonadditive dispersion and induction. Simulations ...

We report full ab initio Hartree-Fock calculation to compute quantum mechanical interaction energies for beta-trypsin/benzamidine binding complex. In this study, the full quantum mechanical ab initio energy calculation for the entire protein complex with 3238 atoms is made possible by using a recently developed MFCC (molecular fractionation with conjugate caps) approach in which the protein mol...

For two electronic states coupled by conical intersections, the line integral of the derivative coupling can be used to construct a complex-valued multiplicative phase factor that makes the real-valued adiabatic electronic wave function single-valued, provided that the curl of the derivative coupling is zero. Unfortunately for ab initio determined wave functions, the curl is never rigorously ze...

A procedure is presented for deriving kinetic and potential-energy functions from experimental data for an arbitrary number of large-amplitude vibrations. As a starting point, the method requires a highquality estimate of the spectroscopic data. We use the previously developed technique of spectrum generation from ab initio calculations to obtain the initial kinetic and potential functions. The...

ABSTRACT The sodium monoxide radical (NaO) is observed in night-glow the Earth’s mesosphere and likely has astronomical importance. This study concerns optical transitions within ground X 2Π state to very low-lying (Te ≈ 2000 cm−1) excited A 2Σ+ state. line list consisting of rovibronic term values, allowed electric dipole transitions, Einstein coefficients, partition functions for varying temp...

Imatinib is an important anticancer drug, which binds specifically to the Abl kinase and blocks its signalling activity. To model imatinib:protein interactions, we have developed a molecular mechanics force field for imatinib and four close analogues, which is consistent with the CHARMM force field for proteins and nucleic acids. Atomic charges and Lennard-Jones parameters were derived from a s...

We perform ab initio molecular dynamics simulations to study the dissociation of NaCl in water. The potential of mean force (PMF) between the two ions is determined using the constrained-force method. The simulation windows corresponding to the contact and solvent-separated minima, and the transition state in between, are further analyzed to determine the changes in the properties of hydration ...

We have parametrized a reactive force field for NaH, ReaxFF(NaH), against a training set of ab initio derived data. To ascertain that ReaxFF(NaH) is properly parametrized, a comparison between ab initio heats of formation of small representative NaH clusters with ReaxFF(NaH) was done. The results and trend of ReaxFF(NaH) are found to be consistent with ab initio values. Further validation inclu...

Six anomalous vibronic feature states [ 2 cm-’ full-width at half-maximum (FWHM), each consisting of -20 partially resolved eigenstates] have been observed in stimulated emission pumping (SEP) spectra of C,D,. Of the two plausible assignments for these features, the one most consistent with spectroscopic observations would imply that the lowest energy c&-bent triplet state of acetylene has To<2...

Ab initio simulations aimed at modelling and interpreting STM induced molecular isomerization of naphthalocyanine molecule are presented. Free energy profile, reaction path and activation energies were obtained using the metadynamics method in the frame of Car-Parrinello Molecular Dynamics (CPMD). We propose a multiscale model of the molecular switch process, based on the Ehrenfest Molecular Dy...