Semi-empirical calculation of second Kerr-effect virial coefficients of atoms and small molecules

2004 ◽  
Vol 389 (4-6) ◽  
pp. 293-297 ◽  
Author(s):  
Uwe Hohm ◽  
Lydia Zarkova
Keyword(s):  
Small Molecules ◽  
Kerr Effect ◽  
Virial Coefficients ◽  
Semi Empirical

Frequency-and Temperature-Dependence of Second Refractivity Virial Coefficients

1993 ◽  
Vol 48 (3) ◽  
pp. 505-513
Author(s):  
Uwe Hohm
Keyword(s):  
Temperature Dependence ◽  
Small Molecules ◽  
Frequency Dependence ◽  
Virial Coefficient ◽  
Virial Coefficients ◽  
Heuristic Approach ◽  
Experimental Values

Abstract A reasonable heuristic extrapolation of a theory given by Buckingham is used to estimate the frequency-and temperature-dependence of the second refractivity virial coefficient. The calculations are carried out for the atoms He, Ne, Ar, Kr, Xe and the small molecules H2 , N2 , O2 , HCl, CO2 , N2O, NH3 , CH4 , C2H4 , and SF6 . In some cases the frequency-dependence of BR (ω, T) is compared with experimental values, showing sometimes considerable deviations between experiment and the heuristic approach used in this work.

A semi-empirical correlation for the estimation of the second virial coefficients of refrigerants

2016 ◽  
Vol 68 ◽  
pp. 242-251 ◽  
Author(s):  
Giovanni Di Nicola ◽  
Gianluca Coccia ◽  
Mariano Pierantozzi ◽  
Matteo Falone
Keyword(s):  
Virial Coefficients ◽  
Empirical Correlation ◽  
Second Virial Coefficients ◽  
Semi Empirical

A new combining rule for fluid mixtures

2009 ◽  
Vol 74 (2) ◽  
pp. 363-391 ◽  
Author(s):  
José Alfredo González-Calderón ◽  
Fernando del Río
Keyword(s):  
Experimental Data ◽  
Small Molecules ◽  
Binary Mixtures ◽  
Electrostatic Interactions ◽  
Virial Coefficient ◽  
Virial Coefficients ◽  
Interaction Parameters ◽  
Effective Interactions ◽  
Fluid Mixtures ◽  
The Cross

We present evidence for the regular behaviour of the Boyle temperature TB in gaseous binary mixtures of small molecules with negligible multipolar moments. We use this regularity to construct a new combining rule for the prediction of the cross interaction u12(r) in those mixtures. The combining rule gives TB of the cross interaction as the harmonic mean of the Boyle temperatures of the pure components. The validity of this harmonic rule is based on experimental data of 28 binary mixtures, whose TB have been obtained from experimental data of the cross virial coefficient B12(T). In determining TB we make use of non-conformal potentials that have been proven to represent very accurately the effective interactions of the molecules investigated. The new combining rule is used to give interaction parameters of several dozens of binary mixtures involving noble gases (Ne, Ar, Kr and Xe), diatomic molecules (N2, O2 and CO) and n-alkanes (from methane to n-octane). These interaction parameters lead to a prediction of cross virial coefficients B12(T) within experimental error. Electrostatic interactions, originating in permanent dipolar, quadrupolar, octupolar and hexadecapolar moments and exemplified by molecules of HCl, CO2, CF4 and SF6, depart from the regular non-polar behaviour.

Calculation of second Kerr effect virial coefficients of H2S

2000 ◽  
Vol 98 (3) ◽  
pp. 135-138 ◽  
Author(s):  
VINCENT W. COULING ◽  
CLIVE GRAHAM
Keyword(s):  
Kerr Effect ◽  
Virial Coefficients

scholarly journals Theoretical Determination of Binding Energies of Small Molecules on Interstellar Ice Surfaces

2021 ◽  
Vol 8 ◽  
Author(s):  
Denis Duflot ◽  
Céline Toubin ◽  
Maurice Monnerville
Keyword(s):  
Carbon Atom ◽  
Small Molecules ◽  
Single Point ◽  
Binding Energies ◽  
Basis Sets ◽  
Adsorption Sites ◽  
Interstellar Ice ◽  
Amorphous Ices ◽  
Semi Empirical

The adsorption of a series of atoms and small molecules and radicals (H, C, N, O, NH, OH, H2O, CH3, and NH3) on hexagonal crystalline and amorphous ice clusters were obtained via classical molecular dynamics and electronic structure methods. The geometry and binding energies were calculated using a QMHigh:QMLow hybrid method on model clusters. Several combination of basis sets, density functionals and semi-empirical methods were compared and tested against previous works. More accurate binding energies were also refined via single point Coupled Cluster calculations. Most species, except carbon atom, physisorb on the surface, leading to rather small binding energies. The carbon atom forms a COH2 molecule and in some cases leads to the formation of a COH-H3O+ complex. Amorphous ices are characterized by slightly stronger binding energies than the crystalline phase. A major result of this work is to also access the dispersion of the binding energies since a variety of adsorption sites is explored. The interaction energies thus obtained may serve to feed or refine astrochemical models. The present methodology could be easily extended to other types of surfaces and larger adsorbates.

Calculation of second Kerr effect virial coefficients of H 2 S

2000 ◽  
Vol 98 (3) ◽  
pp. 135-138
Author(s):  
Vincent W. Couling, Clive Graham
Keyword(s):  
Kerr Effect ◽  
Virial Coefficients
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