Glasser Leslie, von Szentpály László
Nanochemistry Research Institute, Department of Applied Chemistry, Curtin University of Technology, GPO Box U1987, Perth, Western Australia 6845, Australia.
J Am Chem Soc. 2006 Sep 20;128(37):12314-21. doi: 10.1021/ja063812p.
Classical procedures to calculate ion-based lattice potential energies (U(POT)) assume formal integral charges on the structural units; consequently, poor results are anticipated when significant covalency is present. To generalize the procedures beyond strictly ionic solids, a method is needed for calculating (i) physically reasonable partial charges, delta, and (ii) well-defined and consistent asymptotic reference energies corresponding to the separated structural components. The problem is here treated for groups 1 and 11 monohalides and monohydrides, and for the alkali metal elements (with their metallic bonds), by using the valence-state atoms-in-molecules (VSAM) model of von Szentpály et al. (J. Phys. Chem. A 2001, 105, 9467). In this model, the Born-Haber-Fajans reference energy, U(POT), of free ions, M(+) and Y(-), is replaced by the energy of charged dissociation products, M(delta)(+) and Y(delta)(-), of equalized electronegativity. The partial atomic charge is obtained via the iso-electronegativity principle, and the asymptotic energy reference of separated free ions is lowered by the "ion demotion energy", IDE = -(1)/(2)(1 - delta(VS))(I(VS,M) - A(VS,Y)), where delta(VS) is the valence-state partial charge and (I(VS,M) - A(VS,Y)) is the difference between the valence-state ionization potential and electron affinity of the M and Y atoms producing the charged species. A very close linear relation (R = 0.994) is found between the molecular valence-state dissociation energy, D(VS), of the VSAM model, and our valence-state-based lattice potential energy, U(VS) = U(POT) - (1)/(2)(1 - delta(VS))(I(VS,M) - A(VS,Y)) = 1.230D(VS) + 86.4 kJ mol(-)(1). Predictions are given for the lattice energy of AuF, the coinage metal monohydrides, and the molecular dissociation energy, D(e), of AuI. The coinage metals (Cu, Ag, and Au) do not fit into this linear regression because d orbitals are strongly involved in their metallic bonding, while s orbitals dominate their homonuclear molecular bonding.
计算基于离子的晶格势能（U(POT)）的传统方法假定结构单元上存在形式上的整数电荷；因此，当存在显著的共价性时，预计会得到较差的结果。为了将这些方法推广到严格意义上的离子固体之外，需要一种方法来计算：（i）物理上合理的部分电荷δ，以及（ii）与分离的结构组分相对应的明确且一致的渐近参考能量。本文利用冯·森特帕利等人（《物理化学杂志A》2001年，第105卷，9467页）的价态分子中原子（VSAM）模型，对第1族和第11族的一卤化物和一氢化物以及碱金属元素（及其金属键）的这个问题进行了处理。在这个模型中，自由离子M(+)和Y(-)的玻恩-哈伯-法扬斯参考能量U(POT)被电负性均衡后的带电解离产物M(δ)(+)和Y(δ)(-)的能量所取代。部分原子电荷通过等电负性原理获得，分离的自由离子的渐近能量参考因“离子降级能量”IDE = - (1)/(2)(1 - δ(VS))(I(VS,M) - A(VS,Y))而降低，其中δ(VS)是价态部分电荷，(I(VS,M) - A(VS,Y))是产生带电物种的M和Y原子的价态电离势与电子亲和能之差。发现VSAM模型的分子价态解离能D(VS)与我们基于价态的晶格势能U(VS) = U(POT) - (1)/(2)(1 - δ(VS))(I(VS,M) - A(VS,Y)) = 1.230D(VS) + 86.4 kJ mol(-)(1)之间存在非常紧密的线性关系（R = 0.994）。给出了对AuF的晶格能、造币金属一氢化物以及AuI的分子解离能D(e)的预测。造币金属（Cu、Ag和Au）不适合这种线性回归，因为d轨道在它们的金属键中起强烈作用，而s轨道在它们的同核分子键中占主导。
