Showing papers by "Jonathan Tennyson published in 1985"
TL;DR: In this paper, classical and quantum mechanical calculations on the vibrational motions of LiCN using a realistic potential are presented, together with recent results for KCN, using indicators that have been proposed for identifying quantum chaos.
Abstract: Classical and quantum mechanical calculations on the vibrational motions of LiCN using a realistic potential are presented. These, together with recent results for KCN, are analyzed using indicators that have been proposed for identifying quantum chaos. These are nodal structure, dominant coefficient, overlapping avoided crossings, second differences, and spectral distribution. We find an early onset of chaos in LiCN and KCN with good agreement between the indicators. Localized quasiperiodic trajectories and regular states are found well into the chaotic region for both isomers of LiCN. LiCN is a weakly coupled system in contrast to strongly coupled KCN. The utility of the indicators is discussed in the light of these results. The link between floppy molecules and chaos suggests that floppy systems are suitable for the experimental investigation of vibrational chaos.
59 citations
TL;DR: In this paper, the positions and widths of all the low-lying Sigma and Pi resonances in the electron-H2+ collision problem are examined as functions of H2+ geometry.
Abstract: The positions and widths of all the low-lying Sigma and Pi resonances in the electron-H2+ collision problem are examined as functions of H2+ geometry. The scattering calculations reported are based on the R-matrix method and include both coupled-state and polarisation effects non-empirically. Two- and four-coupled-state calculations are presented. Agreement with many of the previous calculations is found although some published data are found to be in error. Predictions for the 2 Sigma g+ to 2 Sigma u+ electronic excitation cross section are also given.
58 citations
TL;DR: In this paper, the electronic excitation of the repulsive b3 Sigma u+ state of H2 from the ground state is studied using the R-matrix method and good agreement is obtained with the results of the linear algebraic method and the Schwinger multichannel formulation.
Abstract: The electronic excitation of the repulsive b3 Sigma u+ state of H2 from the ground state is studied using the R-matrix method. Correlation and polarisation effects are included ab initio. Results are compared with other theoretical work. While previous calculations appear to underestimate the cross section, good agreement is obtained with the results of the linear algebraic method and the Schwinger multichannel formulation. The authors also present elastic scattering cross sections in the same approximation and compare the results with other work. They obtain satisfactory agreement with experimental results.
54 citations
TL;DR: In this paper, the authors reinterpret the high-energy vibrational data on O 3 and HCN and suggest that the observed regular stretching states probably are embedded in the chaotic region.
34 citations
TL;DR: As a result of the deliberations and discussions during the last General Assembly of the IAU in The Hague, it was recommended that Commission 14 become a commission of the Executive Committee as discussed by the authors.
Abstract: As a result of the deliberations and discussions during the last General Assembly of the IAU in The Hague, it was recommended that Commission 14 become a commission of the Executive Committee. The special interdisciplinary role and nature of Comm. 14 were in this way recognized and encouraged.
31 citations
TL;DR: In this paper, exact exact rovibrational calculations are performed for the H3/+, H2D+ and D2H+ molecules using two recent fits to the ab initio potential energy data of Burton et al.
Abstract: Variationally exact rovibrational calculations are performed for the H3/+, H2D+ and D2H+ molecules using two recent fits to the ab initio potential energy data of Burton et al. (1985, Molec. Phys., 55, 527). For the best surface, vibrational fundamentals are vA1 = 3175 cm-1 and vE = 2518 (2521) cm-1 for H3/+; v 1 = 2989 (2992) cm-1, v 2 = 2203 cm-1, and v 3 = 2332 cm-1 for H2D+, and v 1 = 2733 (2737), v 2 = 1965, v 3 = 2027 for D2H+ (where experimental results are given in parenthesis). Rotational constants, which agree well with the experimental constants, where available, are calculated for H3/+ and D2H+. Results are presented for the (0, 1, 0) and (0, 0, 1) states of D2H+ which are yet to be characterized experimentally.
31 citations
TL;DR: In this paper, the authors presented quantum mechanical ro-vibrational calculations for the ArHCl van der Waals complex using Hutson and Howard's empirical M5 potential.
Abstract: Quantum mechanical ro-vibrational calculations are presented for the ArHCl van der Waals complex using Hutson and Howard's empirical M5 potential. Analysis of the nodal structures, second differences and overlapping avoided crossings suggests that the higher bound states of ArHCl are chaotic. This chaos is made evident by perturbing the angular part of the kinetic energy term, e.g. by isotopic substitution or vibrational excitation of HCl. Calculations with J > 0 show increased level crossings but no significant increase in chaos because of an extra nearly good quantum number. The low-lying states of ArHCl appear to be poorly modelled by either the harmonic oscillator or free rotor approximations. Comparison with other molecules for which vibrational chaos has been predicted are made.
27 citations
TL;DR: In this paper, the rotational levels of the (0, 0, 0), (1, 1, 0) and (0, 0, 1) states of H2D+ were fitted and assignments suggested for the spectrum of Shy, Farley and Wing.
Abstract: Ab initio data for the rotational levels of the (0, 0, 0), (0, 1, 0) and (0, 0, 1) states of H2D+ are fitted and assignments suggested for the spectrum of Shy, Farley and Wing (1981, Phys. Rev., A, 24, 1146).
18 citations
TL;DR: In this article, a method of evaluating matrix elements between polynomial basis functions involving the explicit expansion of the operator in terms of the polynomials is proposed, which is shown to have several advantages over the direct evaluation of these matrix elements by Gaussian quadrature, including savings of up to a factor of 6N for an N-dimensional integral.
11 citations
9 citations