Search results for: John N. Murrell

Items from 1 to 13 out of 13 results

article

The origins and later developments of molecular orbital theory

John N Murrell

International Journal of Quantum Chemistry > 112 > 17 > 2875 - 2879

Hund in 1926 speculated on the assignment of quantum numbers for the electronic states of diatomic molecules, basing his assignments on the correlation between the diatomic states and those of the united atom limit. Mulliken, who had earlier considered the problem of this assignment using old quantum theory, followed Hund in 1927, in the new quantum theory, correlating the states of a diatomic molecule...

article

Exact statistical mechanical lattice model and classical Lindemann theory of melting of inert gas solids

Lawrence J. Dunne, John N. Murrell, George Manos

Chemical Physics Letters > 2008 > 456 > 4-6 > 162-165

A modified form of Lindemann’s model shows that the melting points of the heavy inert gases and other effectively spherical molecular species are proportional to the depths of their diatomic potential wells. The success of the model when compared with experiment seems to rely on the almost constant value of the ratio of the fractional volume and entropy changes during fusion. The Lindemann proposal...

article

Exact matrix computation of the statistical mechanics of a cell model of hard sphere phase behaviour

Lawrence J. Dunne, John N. Murrell, George Manos, Mahdi Rekabi

Chemical Physics Letters > 2006 > 421 > 1-3 > 47-51

An exact calculation of the statistical mechanics of a cell model of hard-sphere isotherm behaviour is presented. Our calculation attributes the observed steps in the pressure–volume isotherms to entropic effects caused by the volume of space excluded by the hard core.

article

A search for bound levels of the van der waals molecules: H2(a3Σu+), HeH(X2Σ+), LiH(a3Σ+) and LiHe(X2Σ+)

John N. Murrell, Timothy G. Wright, S. Danko Bosanac

Journal of Molecular Structure: THEOCHEM > 2002 > 591 > 1-3 > 1-9

Calculations based on accurate potentials have been made to search for bound levels of the lowest triplet states of hydrogen and lithium hydride, and the doublet ground states of HeH and LiHe. For the triplet state of H ₂ , a previously reported high quality potential energy curve was employed. For the other three molecules, RCCSD(T) potentials have been calculated over a large range of interatomic...

article

High-quality interatomic potential for Li ⁺ .He

Pavel Soldán, Edmond P.F. Lee, Jérôme Lozeille, John N. Murrell, more

Chemical Physics Letters > 2001 > 343 > 3-4 > 429-436

CCSD(T)/aug-cc-pVQZ and CCSD(T)/aug-cc-pV5Z methods have been employed to obtain accurate interatomic potentials for Li ⁺ .He, from which spectroscopic parameters are derived. A potential is presented using the larger basis set consisting of 91 points (R>=1.3 Å). An accurate value for the long-range D ₄ parameter could be obtained from the potential, but it was not possible to extract...

article

Comparisons in the Behavior of Stable Copper(II), Silver(II), and Gold(II) Complexes in the Gas Phase: Are There Implications for Condensed-Phase Chemistry?

Nicholas R. Walker, Rossana R. Wright, Perdita E. Barran, John N. Murrell, more

Journal of the American Chemical Society > 2001 > 123 > 18 > 4223 - 4227

article

Analytical potential energy surface and quasi-classical dynamics for the reaction LiH(X, ¹ Σ ⁺ )+H( ² S)->Li( ² S)+H ₂ (X, ¹ Σ ⁺ _g )

Lawrence J. Dunne, John N. Murrell, Patrick Jemmer

Chemical Physics Letters > 2001 > 336 > 1-2 > 1-6

A potential energy surface has been derived using ab initio and spectroscopic data for the lowest ² A ^' state of LiH ₂ . Quasi-classical trajectories have been carried for the astrophysically important reaction LiH(X, ¹ Σ ⁺ )+H( ² S)->Li( ² S)+H ₂ (X, ¹ Σ ⁺ _g ). Between 150 and 4000 K the rate is 2-6x10 ^- ...

article

Empirical Potentials for Modeling Solids, Surfaces, and Clusters

Hazel Cox, Roy L. Johnston, John N. Murrell

Journal of Solid State Chemistry > 1999 > 145 > 2 > 517-540

A review of studies that have been made using the Murrell–Mottram two-plus-three-body empirical potential is presented. The explicit many-body nature of the potential is described and the fitting of these potentials to experimental data on one or more solid phases is detailed. Comparisons are made between potentials for various nonmetallic and metallic elements, from which trends in the parameters...

article

Semi-empirical electronic structure methods

John N. Murrell

Journal of Molecular Structure: THEOCHEM > 1998 > 424 > 1-2 > 93-99

The development of semi-empirical electronic structure methods from the early 1930s to the present day is reviewed. The emphasis is on the valence bond and molecular orbital treatments of molecules but some coverage of solids is given, in so far as it follows chemical models. The current position of such theories in respect of the conceptual insight they provide and their success for predictions...

article

An analytic function for the three-body potential of He ₃

Michael J. Cohen, John N. Murrell

Chemical Physics Letters > 1996 > 260 > 3-4 > 371-376

An accurate representation of the three-body potential for the ground state of neutral He ₃ has been obtained by fitting to high quality ab initio data. The calculations show that the 3rd order, triple-dipole dispersion energy is of minimal importance in comparison with the three-body exchange term except at very large internuclear separations. Damping of the triple-dipole term is better...

article

Collision dynamics for small helium cluster ions

S. Danko Bosanac, John N. Murrell

Chemical Physics Letters > 1996 > 254 > 1-2 > 69-72

Classical trajectories have been carried out for the collision of helium atoms with He₂ ⁺ and He₃ ⁺ using a potential energy which includes the effects of dispersion, polarisation and charge exchange. At a collision energy of 0.1 eV the cross-section for atom exchange in He + He₂ ⁺ is calculated to be 21.5Å, exchange occurring through both simple collisions and long-lived complexes...

article

Collision dynamics for small helium cluster ions

S. Danko Bosanac, John N. Murrell

Chemical Physics Letters > 1996 > 254 > 1-2 > 69-72

Classical trajectories have been carried out for the collision of helium atoms with He₂⁺ and He₃⁺ using a potential energy which includes the effects of dispersion, polarisation and charge exchange. At a collision energy of 0.1 eV the cross-section for atom exchange in He + He₂⁺ is calculated to be 21.5Å, exchange occurring through both simple collisions and long-lived complexes. However, even for...

article

Towards reliable modelling of large clusters: on the overall accuracy of the diatomics-in-molecule method for rare gas cluster ions

Fedor Yu. Naumkin, Peter J. Knowles, John N. Murrell

Chemical Physics > 1995 > 193 > 1-2 > 27-36

The accuracy of the diatomics-in-molecules (DIM) method is examined for the case of rare gas ionic clusters through a series of careful calibration calculations. Ab initio potential energy functions for Rg ⁺ ₃ and Rg ⁺ ₄ (Rg = He, Ne, Ar) are compared with the DIM model, taking diatomic potentials computed at exactly the same level of ab initio theory as input. For Ne ⁺...

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AB INITIO CALCULATIONS (1)
ACCURATE POTENTIALS (1)
BOUND STATES (1)
DIATOMIC MOLECULE (1)
H2 (1)
HEH (1)
ISOTOPOMERS (1)
LIH (1)
LIHE (1)
MODERN QUANTUM MECHANICAL CALCULATIONS (1)
MOLECULAR ORBITAL THEORY (1)
MOLECULAR ORBITALS (1)
PARAMAGNETISM OF O2 (1)
SEMI EMPIRICAL METHODS (1)
SOLIDS (1)
TRIPLET STATES (1)
VALENCE BOND (1)
VAN DER WAALS (1)
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Elsevier (11)
ACS (1)
Wiley (1)

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