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Full-Text Articles in Physical Sciences and Mathematics

Monte Carlo Simulation Of Acetonitrile Clusters [Ch3cn] N , N=2–256: Melting Transitions And Even/Odd Character Of Small Clusters (N=2–9), Heat Capacities, Density Profiles, Fractal Dimension, Intracluster Dimerization, And Dipole Orientation, D. Wright, M. Samy El-Shall Jan 1994

Monte Carlo Simulation Of Acetonitrile Clusters [Ch3cn] N , N=2–256: Melting Transitions And Even/Odd Character Of Small Clusters (N=2–9), Heat Capacities, Density Profiles, Fractal Dimension, Intracluster Dimerization, And Dipole Orientation, D. Wright, M. Samy El-Shall

Chemistry Publications

The thermodynamic and structural properties of acetonitrile clusters [CH3CN] N , N=2–15, 20, 30, 60, 128, and 256 have been investigated using Monte Carlo simulation. Interactions in the small clusters (N≤9) are dominated by antiparallel pairing of the molecular dipoles. The simulations reveal rigid ↔ fluid (melting) transitions with a remarkable even–odd alternation in the transition temperatures for the N=2–9 clusters. The higher melting temperatures of the even‐N clusters arise as consequences of the antiparallel paired dipoles which provide favorable electrostatic interactions. Even–odd alternation has also been observed in the configurational energies and …


Gas Phase Clustering Of N2 Molecules On To Tio+: Comparison With Ti+ And Evidence For The Octahedral Structure Of Tio+(N2)5, George M. Daly, M. Samy El-Shall Jan 1994

Gas Phase Clustering Of N2 Molecules On To Tio+: Comparison With Ti+ And Evidence For The Octahedral Structure Of Tio+(N2)5, George M. Daly, M. Samy El-Shall

Chemistry Publications

A striking difference in the clustering efficiency of Ti+ and TiO+ toward N2 or O2 has been observed in a laser vaporizationhigh pressure mass spectrometric source. Evidence for the magic number n=5 within the sequence TiO+(N2) n is presented. The results are consistent with an octahedral structure for TiO+(N2)5.


Ab Initio Equilibrium Constants For H2o–H2o And H2o–Co2, Nancy Renyou Zhang, Donald D. Shillady Jan 1994

Ab Initio Equilibrium Constants For H2o–H2o And H2o–Co2, Nancy Renyou Zhang, Donald D. Shillady

Chemistry Publications

Ab initio 6‐31G** electronic structure calculations have been used to determine the minimum energy geometries and vibrational frequencies of molecular clusters of water and carbon dioxide. Application of statistical thermodynamics leads to theoretical equilibrium constants for gas phase dimerization of water and the formation of an adduct of carbon dioxide with water.The low energy vibrations of the clusters lead to much larger contributions to the vibrational partitioning of the energy than do the fundamental vibrations of the monomeric species. A new ‘‘Harmonic‐Morse’’ formula is derived to estimate anharmonicity from optimized harmonic frequencies and two additional values on the potential surface …