Environmental dependence of screened tight-binding parameters in La2Ni10H14

The environmental dependence of screened tight-binding (TB) parameters in L a2Ni10H14 has been examined within the two-centre orthogonal TB scheme. The H-Ni sigma bond integral is found to be transferable between the different H-Ni pairs, whereas the Ni-Ni bond integrals are greatly affected by the p resence of the interstitial hydrogen so that they are not transferable. The bond energy of the interstitial hydrogen is reasonably well described with in the second moment approximation, due to the fact that the majority of th e constituent atoms of the host alloy are nickel atoms with almost filled d states. This result supports the use of models such as the embedded-atom m ethod and the Finnis-Sinclair potentials in which the directionality of the bonding is not explicitly treated. (C) 2000 Elsevier Science S.A. All righ ts reserved.