Relativistic modifications of inter-ionic potentials in lead fluoride

Pyper, N.C.; Marketos, P.; Malli, Gulzari

doi:10.1088/0022-3719/20/29/009

Cited by 34 publications

(84 citation statements)

References 43 publications

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“…Both potentials serve to compress the anion relative to its free state. 35,36 U ov (R) then results from the overlap between the optimized wave functions summed over pairs of ions. The model fitted to ab initio data in this form is termed the compressible-ion model ͑CIM͒.…”

Section: Problems Of Simulating Oxidesmentioning

confidence: 99%

Transferable atomistic model to describe the energetics of zirconia

1996

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We have investigated the energies of a number of phases of ZrO 2 using models of an increasing degree of sophistication: the simple ionic model, the polarizable ion model, the compressible ion model, and finally a model including quadrupole polarizability of the oxygen ions. The three structures which are observed with increasing temperatures are monoclinic, tetragonal, and cubic ͑fluorite͒. Besides these we have studied some hypothetical structures which certain potentials erroneously predict or which occur in other oxides with this stoichiometry, e.g., the ␣-PbO 2 structure and rutile. We have also performed ab initio density functional calculations with the full-potential linear combination of muffin-tin orbitals method to investigate the cubictetragonal distortion. A detailed comparison is made between the results using classical potentials, the experimental data, and our own and other ab initio results. The factors which stabilize the various structure are analyzed. We find the only genuinely transferable model is the one including compressible ions and anion polarizability to the quadrupole level. ͓S0163-1829͑96͒00334-7͔

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Section: Problems Of Simulating Oxidesmentioning

confidence: 99%

Transferable atomistic model to describe the energetics of zirconia

1996

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“…For the case of ions in ionic crystals, the considerable body of literature thereby generated has been reviewed recently [14]. Surprisingly, however, an examination of the papers published before the early nineteen eighties reveals for any one ion a wide range of values for its polarizability without providing any criteria for assessing their reliability.…”

Section: Introductionmentioning

confidence: 99%

“…The environmentally induced modifications of the polarizability of an ion in a crystal can be considered to consist of two different contributions [14][15][16][17][18][19][20]. The first of these, which would be the only contribution if the wavefunctions of the ion overlapped only negligibly with those of neighbouring ions, is the modification caused by the purely electrostatic fields generated by all the other ions in the crystal.…”

Section: Introductionmentioning

confidence: 99%

“…This method must often be used because the size and importance of relativistic effects [14,22] currently prevents the ab initio quantum chemistry methods from being applied to solids containing ions of high nuclear charge. The ab initio quantum chemistry calculations [15][16][17] have not only provided the most accurate values currently available for the polarizabilities of the light cations Li +, Na § K § Mg § and Ca + + but also have shown that these polarizabilities are essentially insensitive to their environment.…”

Section: Introductionmentioning

confidence: 99%

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The polarizabilities of species present in ionic solutions

1992

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Values for the polarizabilities of both mono and multinuclear anions in aqueous solution at infinite dilution are derived. This is achieved by subtracting from each experimentally determined molar polarizability, the polarizability of the cation as well as the total change caused by this cation in the polarizabilities of neighbouring water molecules. Each cation polarizability was taken to be unchanged from its value known from previous work to be common to both the free ion and the ion in an ionic crystal. The required values of the total changes in the polarizabilities of water molecules influenced by cations are derived from the experimental molar polarizabilities by two different methods. The first of these yields results which are essentially identical to those derived from the second approach in which the value for Li + is fixed from ab initio quantum chemistry computations including electron correlation effects.The polarizability of each anion in aqueous solution is found to be considerably reduced from that of the free ion and to be close to that of the anion in its solid caesium salt.

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“…The result that the 2s orbital is only compressed at those distances where the term AЈ exp(ϪbЈ͓R Ϫ␦Ј)͔ becomes appreciable confirms that this compression does indeed arise from the direct interaction of the O Ϫ2 2s electrons with the charge distributions of neighboring ions in the crystal. The term 1 2 ␥Ј␦Ј 2 thus describes the energy needed to change the charge distribution of the 2s orbital, not from its form optimal for a free O Ϫ ion, which is the reference species in the definition of E re (R), but from the form it would have if it did not directly interact with its environment in the crystal.…”

Section: The Rearrangement Energy and The Cation-anion Termsmentioning

confidence: 99%

A physically transparent and transferable compressible ion model for oxides

Marks

Finnis

Harding

et al. 2001

The Journal of Chemical Physics

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Approaching the bulk limit with finite cluster calculations using local increments: The case of LiH A one-electron model for the aqueous electron that includes many-body electron-water polarization: Bulk equilibrium structure, vertical electron binding energy, and optical absorption spectrum J. Chem. Phys. 133, 154506 (2010); 10.1063/1.3490479The nature of metal-oxide chemical bond: Electronic structure of PdMgO and PdOMg molecules A new compressible ion model for describing the energetic components of the cohesive energy of a fully ionic crystal is developed and tested using previous ab initio results for three cubic phases of MgO. This model is physically highly transparent and improves on previous compressible ion models in two ways. First, the short-range cation-anion interaction and the rearrangement energy needed to convert a free O Ϫ ion plus a free electron into an O Ϫ2 ion having a form optimal for its in-crystal environment are decomposed into the major contributions originating from the six outermost anion electrons plus smaller terms generated by the two 2s electrons. This model transfers to the B2 and B3 phases of MgO after parametrization on the ab initio data for the B1 phase even more accurately than previous compressible ion models. Second, the separate modeling of the repulsive ͑permutation͒ and attractive ͑penetration͒ components of the short-range anionanion interactions enables the new model to describe their subtle dependencies on the in-crystal anion environment that lie beyond the scope of previous models. The new model is also used to illuminate the behavior of two fluorite oxides.

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Relativistic modifications of inter-ionic potentials in lead fluoride

Cited by 34 publications

References 43 publications

Transferable atomistic model to describe the energetics of zirconia

Transferable atomistic model to describe the energetics of zirconia

The polarizabilities of species present in ionic solutions

A physically transparent and transferable compressible ion model for oxides

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