Publications

@article{Raghavan1985,
title = {Rotational energy transfer in HF-Li collisions},
author = {K Raghavan, S Upadhyay, N Sathyamurthy and R Ramaswamy},
url = {https://pubs.aip.org/aip/jcp/article-pdf/83/4/1573/11110051/1573\_1\_online.pdf},
doi = {10.1063/1.449394},
issn = {0021-9606},
year = {1985},
date = {1985-08-15},
journal = {The Journal of Chemical Physics},
volume = {83},
number = {4},
pages = {1573–1577},
abstract = {We report state‐to‐state integral inelastic cross sections for rotational energy transfer in rigid rotor HF–Li collisions, at a relative translational energy of 8.7 kcal mol−1. The results have been analyzed in terms of power gap law, information theoretic synthesis using energy and angular momentum constraints, and energy corrected sudden and energy corrected sudden‐power law scaling relations.},
keywords = {Perturbation},
pubstate = {published},
tppubtype = {article}
}

@article{Ramaswamy1984bb,
title = {Quasiperiodic quantum states},
author = {R Ramaswamy},
url = {https://pubs.aip.org/aip/jcp/article-pdf/80/12/6194/11014720/6194\_1\_online.pdf},
doi = {10.1063/1.446721},
issn = {0021-9606},
year = {1984},
date = {1984-06-15},
journal = {The Journal of Chemical Physics},
volume = {80},
number = {12},
pages = {6194–6199 },
abstract = {We show that the Hose–Taylor criterion of quantum quasiperiodicity can be recovered from low‐order nondegenerate perturbation theory. It is seen that this mnemonic, which purports to identify energy levels which can be obtained by quantizing classical quasiperiodic motions, can lead to contradictions when applied to systems which are more semiclassical than that treated previously. These discrepancies arise since the criterion is both perturbation scheme and basis set dependent: the correlation between the semiclassical quantization and such a definition of quantum quasiperiodic behavior is not straightforward. As the underlying search is for a quantum KAM‐like theory (in particular for near‐separable systems which are typical of molecular vibrational Hamiltonians) some possibilities are discussed.},
keywords = {Perturbation, Quantum State},
pubstate = {published},
tppubtype = {article}
}

@article{Ramaswamy1981,
title = {Perturbative examination of avoided crossings},
author = {R Ramaswamy and R A Marcus},
url = {https://doi.org/10.1063/1.441201},
doi = {10.1063/1.441201},
issn = {0021-9606},
year = {1981},
date = {1981-01-15},
journal = {The Journal of Chemical Physics},
volume = {74},
number = {2},
pages = {1379–1384},
abstract = {Quantum perturbation theory is used to examine the eigenvalues of a nonseparable Hamiltonian system in the classically regular and irregular regimes. As a function of the perturbation parameter, the eigenvalues obtained by exact (matrix diagonalization) methods undergo an avoided crossing. In the present paper perturbation theory is used as an approximate method to predict the locations of such avoided crossings in energy‐parameter space. The sparsity of such avoided crossings in the Hénon–Heiles system is seen to produce regular sequences in the eigenvalues even when the classical motion is predominantly chaotic.},
keywords = {Henon-Heiles, Nonintegrable Hamiltonian Systems, Perturbation},
pubstate = {published},
tppubtype = {article}
}

@article{Ramaswamy1981b,
title = {The onset of chaotic motions in deterministic systems},
author = {R Ramaswamy and R A Marcus
},
url = {https://doi.org/10.1063/1.441202},
doi = {10.1063/1.441202},
issn = {0021-9606},
year = {1981},
date = {1981-01-15},
journal = {The Journal of Chemical Physics},
volume = {74},
number = {2},
pages = {1385–1393},
abstract = {In the present paper the classical counterpart of the quantum avoided crossing method for detecting chaos is described using classical (Lie‐transform) perturbation theory and a grid of action variables. The results are applied to two systems of coupled oscillators with cubic and quartic nonlinearities. The plots of energy of members of the grid versus the perturbation parameter provide a visual description for predicting the onset of chaos.},
keywords = {Chaos, Coupled Oscillators, Perturbation},
pubstate = {published},
tppubtype = {article}
}

@article{Ramaswamy1980,
title = {Semiclassical quantization of multidimensional systems},
author = {R Ramaswamy, P Siders and R A Marcus
},
url = {https://doi.org/10.1063/1.439939},
doi = {10.1063/1.439939},
issn = {0021-9606},
year = {1980},
date = {1980-11-15},
journal = {The Journal of Chemical Physics},
volume = {73},
number = {10},
pages = {5400–5401},
abstract = {Low order classical perturbation theory is used to obtain semiclassical eigenvalues for a system of three anharmonically coupled oscillators. The results in the low energy region studied here agree well with the ’’exact’’ quantum values. The latter had been calculated by matrix diagonalization using a large basis set.},
keywords = {Coupled Oscillators, Perturbation},
pubstate = {published},
tppubtype = {article}
}