Upakarasamy Lourderaj

Learn More
The interface for VENUS and NWChem, and the resulting software package for direct dynamics simulations are described. The coupling of the two codes is considered to be a tight coupling since the two codes are compiled and linked together and act as one executable with data being passed between the two codes through routine calls. The advantages of this type(More)
A survey is presented of theoretical models and computational studies for unimolecular reaction dynamics. Intrinsic RRKM and non-RRKM dynamics are described, and properties of the unimolecular reactant's classical phase space giving rise to these dynamics are discussed. Quantum dynamical calculations of isolated resonances and state-specific decomposition(More)
In the previous work of Mikosch et al. [Science 319, 183 (2008)], ion imaging experiments were used to study the Cl(-) + CH3I → ClCH3 + I(-) reaction at collision energies E(rel) of 0.39, 0.76, 1.07, and 1.9 eV. For the work reported here MP2(fc)/ECP/d direct dynamics simulations were performed to obtain an atomistic understanding of the experiments. There(More)
All species involved in the multichannel decomposition of gas-phase dimethyl methylphosphonate (DMMP) were investigated by electronic structure calculations. Geometries for stationary structures along the reaction paths, were fully optimized with the MP2 method and the B3LYP and MPW1K DFT functionals, and the 6-31G*, 6-31++G**, and aug-cc-pVDZ basis sets.(More)
In previous research [J. Chem. Phys. 111, 3800 (1999)] a Hessian-based integration algorithm was derived for performing direct dynamics simulations. In the work presented here, improvements to this algorithm are described. The algorithm has a predictor step based on a local second-order Taylor expansion of the potential in Cartesian coordinates, within a(More)
We have investigated the solid-state photobehavior of a broad set of pyridine-3-carboxaldehydes 1-5. The introduction of a heteroatom into mesitaldehydes as in aldehydes 1 raises the question of conformational preference in the solid state. The preferred conformations have been unequivocally established from X-ray crystal structure analyses of two of the(More)
The ground-state properties of the monomer and the dimer of formic acid, acetic acid, and benzoic acid have been investigated using Hartree-Fock (HF) and density functional theory (DFT) methods using the 6-311++G(d,p) basis set. Some of the low-lying excited states have been studied using the time-dependent density functional theory (TDDFT) with LDA and(More)
Study of the dynamics of H2CO confined within graphene sheets and sensing of H2CO by graphene require an analytic representation of the intermolecular potential between H2CO and graphene. To develop an intermolecular potential for H2CO interacting with graphene, ab initio calculations were performed at the MP2/MG3S, B97-D/MG3S and LPNO-CEPA/1/CBS levels of(More)
By elucidating the mechanism of the simplest electrophilic substitution reaction of ferrocene, it was found that the verification of the protonation reaction has been a difficulty. In the work reported here, ab initio chemical dynamics simulations were performed at B3LYP/DZVP level of theory to understand the atomic level mechanisms of protonation and(More)