摘要:

Ab initiopotential energy surfaces including the vibrational coordinate dependence are presented for CO… He and CO… H2using the coupled cluster method with Brueckner orbitals. The interaction energy is calculated using the supermolecule approach. The calculation of rate constants for the vibrational relaxation of CO(v= 1) by He and their comparison with the experimentally measured values over the temperature range 40–300 K is used to test the accuracy of the CO… He surface. Comparison with results from an earlier surface calculated by symmetry adapted perturbation theory shows that the two surfaces have similar scattering characteristics and reproduce the experimental measurements to a similar level of accuracy. The potential surface for the CO… H2system is presented as raw data in anticipation of future calculations.

ISSN:0026-8976    

DOI:10.1080/00268970009483403

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Single-crystal variable temperature EPR, optical and polycrystalline magnetic susceptibility studies have been made on a novel six-coordinate Ag(II) complex. Temperature dependent EPR studies on pure single crystals of this compound reveal that dynamic Jahn-Teller distortion operates above 230 K, between 230 K and 120K static Jahn-Teller distortion sets in and below 110 K there is evidence of exchange interaction. Crystalgvalues were obtained by least-squares fitting with the data obtained from the orientation dependent EPR spectra of the undiluted single crystal of this complex at 300 K and 77 K. From an optical study the Jahn-Teller stabilization energy is found to be ∼2250cm−1. Comparison of Absmaxvalues for other silver(II) compounds enables us to conclude that the formal geometry of this complex is a tetragonally distorted octahedral. Infrared spectra of this complex were also recorded over a wide range of temperature. Magnetic susceptibility measurements over a wide range of temperature on the powder sample of this compound reveal that the complex is antiferromagnetically coupled in the temperature range 5–40 K with 2J= 0.906cm−1, and above 40K it is ferromagnetically coupled with 2J= +7.4cm−1. The effective magnetic moment (μeff) of this complex has been compared with that of a series of other silver(II) complexes available in the literature. Finally, the spectral and magnetic data of this complex have been compared with those of a corresponding isostructural and isomorphous copper(II) complex.

ISSN:0026-8976    

DOI:10.1080/00268970009483404

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Fourier transform spectra have been recorded for carbon disulphide CS2in the region of the 4ν2+ ν3band near 3100 cm−1. The data analysis has determined new molecular constants. Bands were also observed for the isotopomer12C32S34S.

ISSN:0026-8976    

DOI:10.1080/00268970009483405

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Square-well homo-nuclear and hetero-nuclear diatomic fluids are studied using the Ornstein-Zernike equation and the recently proposed RHNC-VM closure. Monte Carlo canonical simulations have been performed to complete recent literature simulation data. The integral equation thermodynamic and structural results are compared with these and literature simulation data at three elongations over a large range of densities and temperatures. The RHNC-VM theory agrees excellently with the simulation thermodynamic and structural results. Its accuracy revealed slight errors in simulation data in work by Lisal and Nezbeda [1999,Molec. Phys.,96, 335]. The data have been re-simulated.

ISSN:0026-8976    

DOI:10.1080/00268970009483406

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

We present the second-order thermodynamic perturbation theory (TPT2) and the dimer statistical associating fluid theory (SAFTD) equations of state for mixtures consisting of hetero-nuclear hard chain molecules based on extensions of Wertheim's theory for associating fluids. The second-order perturbation theory, TPT2, is based on the hard sphere mixture reference fluid. SAFTD is an extension of TPT1 (= SAFT) and is based on the non-spherical (hard disphere mixture) reference fluid. The TPT2 equation of state requires only the contact values of the hard sphere mixture site-site correlation functions, while the SAFTD equation of state requires the contact values of site-site correlation functions of both hard sphere and hard disphere mixtures. We test several approximations for site-site correlation functions of hard disphere mixtures and use these in the SAFTD equation of state to predict the compressibility factor of copolymers. Since simulation data are available only for a few pure copolymer systems, theoretical predictions are compared with molecular simulation results for the compressibility factor of pure hard chain copolymer systems. Our comparisons show a very good performance of TPT2, which is found to be more accurate than TPT1 (= SAFT). Using a modified Percus-Yevick site-site correlation function SAFTD is found to represent a significant improvement over SAFT and is slightly more accurate than TPT2. Comparison of SAFTD with generalized Flory dimer (GFD) theory shows that both are equivalent at intermediate to high densities for the compressibility factor of copolymer systems investigated here.

ISSN:0026-8976    

DOI:10.1080/00268970009483407

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

ISSN:0026-8976    

DOI:10.1080/00268970009483408

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

ISSN:0026-8976    

DOI:10.1080/00268970009483409

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

ISSN:0026-8976    

DOI:10.1080/00268970009483410

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor