Intermolecular energy, structure and stability of regular stacks of tetrathiafulvalene (TTF) and tetracyanoquinodimethane (TCNQ)

Abstract

The lattice energy of isolated, regular tetrathiafulvalene (C6H484) and tetracyanoquinodimethane (C12H4N4) segregated and mixed stacks was minimized for four structural parameters; a longitudinal and transverse slip of neighbouring molecules relative to each other, a rotation of a neighbouring molecule 0567-7394/81/040529-07501.00 perpendicular to the molecular planes and the perpendicular distance between two neighbouring molecules. The van der Waals and repulsive interactions only were calculated from atom-atom potentials. The absolute minima of the lattice energies were achieved at stack structures slipped longitudinally with all stack parameters deviating less than about 0

Lattice energy, structure and stability of three-dimensional tetrathiafulvalenium 7,7,8,8-tetracyanoquinodimethanide (TTF–TCNQ) models with segregated and mixed stacks

“…However, quantum-mechanical calculation, although more sophisticated and provided with the perspective of the prediction of the charge transfer, explains an even lower fraction of this enthalpy (Metzger, 1981). A second limitation had already appeared in our stack-structure predictions Govers, 1981). Only the observed structures of TTF and TCNQ segregated stacks with longitudinal molecular slip could be predicted and not the observed TTF stacks with eclipsed configuration and TCNQ stacks slipped transversally.…”

“…~$ Williams & Wallwork (1968). atom-atom potentials (Govers, 1981(Govers, , 1982. In this way we obtained a crude minimum with values of the structural parameters, around which we constructed smaller ranges for the final run.…”

“…The one-dimensional structures of TTF and TCNQ segregated and mixed stacks can be predicted partly, when the atom-atom approximation (Kitaigorodskii, 1973) is used for the calculation of stack energy and this energy is minimized for the relevant structural parameters Govers, 1981). This prediction can be considered the first step in a more complete three-dimensional calculation of stable lattice structures of organic conductors like TTF-TCNQ.…”

Intermolecular energy, structure and stability of regular stacks of tetrathiafulvalene (TTF) and tetracyanoquinodimethane (TCNQ): erratum

“…for the calculations applying set 1 by Govers (1978) with its short summation limits. Therefore all calculations by Govers (1981) which apply set 1 were performed again after correction of the program error.…”

Bibliography of Mathematical Crystallography

“…Therefore all calculations by Govers (1981) which apply set 1 were performed again after correction of the program error.…”