Srinivasan S Iyengar

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A new methodology to perform hybrid empirical/ab-initio molecular dynamics is presented. The method combines the well-established hybrid ONIOM scheme with the recently developed ADMP (Atom-Centered Density Matrix Propagation) approach, where the one electron density matrix expanded in an atom-centered Gaussian basis set is propagated as electronic variables(More)
We discuss hybrid quantum-mechanics/molecular-mechanics (QM/MM) and quantum mechanics/quantum mechanics (QM/QM) generalizations to our recently developed quantum wavepacket ab initio molecular dynamics methodology for simultaneous dynamics of electrons and nuclei. The approach is a synergy between a quantum wavepacket dynamics, ab initio molecular dynamics,(More)
A method of analysis is introduced to probe the spectral features obtained from ab initio molecular dynamics simulations. Here, the instantaneous mass-weighted velocities are projected onto irreducible representations constructed from discrete time translation groups comprising operations that invoke the time-domain symmetries (or periodic phase space(More)
Molecular structure and motion determine properties including spectroscopy and reactivity. We study problems of fundamental chemical interest, 1,2,3,4,5 including those with applications in biological enzyme catalysis 6,7,8 , atmospheric chemistry 9 , and nano-science using theoretical and computational chemistry. We specialize in the development of new(More)
In a recent publication, we introduced a computational approach to treat the simultaneous dynamics of electrons and nuclei. The method is based on a synergy between quantum wave packet dynamics and ab initio molecular dynamics. Atom-centered density-matrix propagation or Born-Oppenheimer dynamics can be used to perform ab initio dynamics. In this paper,(More)
We present a rigorous strategy, based on Stieltjes series and Padé approximants, to obtain suitable bounds for extrapolation of the quantum chemical correlation energy. Computational tests are performed for the second-order Møller–Plesset (MP2) correlation energy, and the bounds obtained are tight enough for practical calculational purposes: The associated(More)
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