The Atom-Atom Potential Method

Pertsin, Alexander J.; Kitaigorodsky, Alexander I.

doi:10.1007/978-3-642-82712-9_3

Cited by 38 publications

(34 citation statements)

References 109 publications

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“…There has been a debate on whether the (6-exp) and similar formulations are adequate to quantitatively describe the intermolecular potential energy of aromatics, or whether the introduction of other terms in the potential expression is necessary (Kitaigorodskii, 1973(Kitaigorodskii, , 1978Williams, 1974;Williams & Starr, 1977). Our line of thought is in agreement with recent views (Pertsin & Kitaigorodskii, 1987) on nonbonded potentials in general; the use of optimized potentials which do not include explicit Coulomb terms does not mean that electrostatic interactions are altogether neglected. The potentials we use here have been shown to fit the static properties of aromatic crystals reasonably well and their adequacy is established from previous work (Mirsky, 1976;Gavezzotti, 1982;Gavezzotti & Desiraju, 1988).…”

Section: Structure Types For Aromatic Hydrocarbonssupporting

confidence: 90%

Crystal structures of polynuclear aromatic hydrocarbons. Classification, rationalization and prediction from molecular structure

Desiraju¹,

Gavezzotti²

1989

Acta Crystallogr B Struct Sci

554

509

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Section: Structure Types For Aromatic Hydrocarbonssupporting

confidence: 90%

Crystal structures of polynuclear aromatic hydrocarbons. Classification, rationalization and prediction from molecular structure

Desiraju¹,

Gavezzotti²

1989

Acta Crystallogr B Struct Sci

554

509

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“…In this case the model includes the entropy factor implicitly, and the lattice parameters found by direct minimization of U should actually refer to the room temperature. The accuracy of the atom-atom approach is corroborated by extensive statistics obtained for organic molecular crystals [32,33,34]. Typically it provides the accuracy level of ca.…”

Section: Atom-atom Potentials Methodsmentioning

confidence: 90%

“…In order to avoid unnecessary complications, we limit our task in the present paper to checking the possibility of applying the simplest method of modeling intermolecular interactions -atom-atom potentials [32] -to crystals formed by spin-active complexes. The method assumes that the energy of the molecular crystal (calculated relative to the system of isolated molecules) can be represented as:…”

Section: Atom-atom Potentials Methodsmentioning

confidence: 99%

Modeling molecular crystals formed by spin-active metal complexes by atom–atom potentials

Sinitskiy

Tchougréeff

Tokmachev

et al. 2009

Phys. Chem. Chem. Phys.

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We apply the atom-atom potentials to molecular crystals of iron (II) complexes with bulky organic ligands. The crystals under study are formed by low-spin or high-spin molecules of Fe(phen)2(NCS)2 (phen = 1,10-phenanthroline), Fe(btz)2(NCS)2 (btz = 5,5 ′ ,6,6 ′ -tetrahydro-4H,4 ′ H -2,2 ′ -bi-1,3-thiazine), and Fe(bpz)2(bipy) (bpz = dihydrobis(1-pyrazolil)borate, and bipy = 2,2 ′ -bipyridine). All molecular geometries are taken from the X-ray experimental data and assumed to be frozen. The unit cell dimensions and angles, positions of the centers of masses of molecules, and the orientations of molecules corresponding to the minimum energy at 1 atm and 1 GPa are calculated. The optimized crystal structures are in a good agreement with the experimental data. Sources of the residual discrepancies between the calculated and experimental structures are discussed. The intermolecular contributions to the enthalpy of the spin transitions are found to be comparable with its total experimental values. It demonstrates that the method of atom-atom potentials is very useful for modeling organometalic crystals undergoing the spin transitions.

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“…Although PE can be related to the crystal sublimation energy (Pertsin & Kitaigorodski, 1987;Williams & Starr, 1977;Gavezzotti, 1989) we regard it in this context as no more than a weighted sum of intermolecular separations in the crystal, or an overall index of the packing propensity for a given molecule -in other words, the one readily available link between molecular and crystal structures. Parameters have always been fitted to a small number of properties on a restricted sample of test crystals, and transferability to a wider range of molecular types has never really been tested.…”

Section: Packing Energiesmentioning

confidence: 99%

Crystal packing of hydrocarbons. Effects of molecular size, shape and stoichiometry

Gavezzotti¹

1990

Acta Crystallogr B Struct Sci

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275practically completely explained in terms of modulations of the average structure which are of the £2 symmetry, even though the average crystal structure corresponds to a frozen-in £, modulation.We argue that the short-range order, which tends locally to preserve the c-glide plane, is due to dipoledipole interactions between molecules. On the other hand, the stability of the lattice over a long range (corresponding to wavevectors close to q = 0) is governed by the short-range repulsive interactions and the ability of the molecules to form a closely packed structure in three different crystallographic planes. In agreement with the general conclusions of Kitaigorodsky (1973) the BEMB2 molecules are more easily able to do this in the space group P21 than in Pc. The 'hole' represents a range of wavevectors for which the strain from the packing forces, as a result of the local breaking of the P21 symmetry, outweighs the energy gained from the short-range ordering of the molecular dipoles. sities, a partitioning of the calculated PE over contact types, the average PE per atom in the molecule, and the number of contacts per atom within a 7/k sphere. The molecular coordination number in hydrocarbon crystals is studied by partitioning the PE in successive shells of four to twelve neighbour molecules; the first (four-molecule) shell contributes 33 to 77% of PE, depending on various factors; the contribution of the twelve-molecule shell is invariably close to 100%.

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The Atom-Atom Potential Method

Cited by 38 publications

References 109 publications

Crystal structures of polynuclear aromatic hydrocarbons. Classification, rationalization and prediction from molecular structure

Crystal structures of polynuclear aromatic hydrocarbons. Classification, rationalization and prediction from molecular structure

Modeling molecular crystals formed by spin-active metal complexes by atom–atom potentials

Crystal packing of hydrocarbons. Effects of molecular size, shape and stoichiometry

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