Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Bergstraße 66c, 01069 Dresden, Germany.
Molecules. 2021 Mar 11;26(6):1539. doi: 10.3390/molecules26061539.
This work presents a method to move beyond the recently introduced atomic fragment approximation. Like the bare atomic fragment approach, the new method is an ab initio, parameter-free, orbital-free implementation of density functional theory based on the bifunctional formalism that treats the potential and the electron density as two separate variables, and provides access to the Kohn-Sham Pauli kinetic energy for an appropriately chosen Pauli potential. In the present ansatz, the molecular Pauli potential is approximated by the sum of the bare atomic fragment approach, and a so-called deformation potential that takes the interaction between the atoms into account. It is shown that this model can reproduce the bond-length contraction due to multiple bonding within the list of second-row homonuclear dimers. The present model only relies on the electron densities of the participating atoms, which themselves are represented by a simple monopole expansion. Thus, the bond-length contraction can be rationalized without referring to the angular quantum numbers of the participating atoms.
这项工作提出了一种超越最近引入的原子碎片近似的方法。与基本的原子碎片方法一样，新方法是一种基于双功能形式主义的从头算、无参数、无轨道的密度泛函理论实现，该形式主义将势和电子密度视为两个独立的变量，并提供了对适当选择的 Pauli 势的 Kohn-Sham Pauli 动能的访问。在目前的假设中，分子 Pauli 势由基本原子碎片方法的和一个所谓的变形势之和近似，该变形势考虑了原子之间的相互作用。结果表明，该模型可以再现第二列同核双原子分子列表中由于多重键合而导致的键长收缩。目前的模型仅依赖于参与原子的电子密度，而电子密度本身由简单的单极展开表示。因此，无需参考参与原子的角量子数，就可以合理化键长收缩。
