縮減交互作用對單原子和雙原子分子化學特性之影響

我們檢視了縮減交互作用對於各個分子特性所造成的影響。在計算中，我們以互補高斯誤差函數取代原本的距離反比庫倫交互作用，並使用CCSD(T)、CCSD、MP2、Hartree-Fock、SR-LDA、SR-PBE等方法進行計算。其中我們選擇CCSD(T)的結果作為參考值並和其他方法的結果作比較。對於各個測試分子，我們計算了原子化能量、游離能、電子親和力、fundamental gap，以及最高佔據分子軌道能量、最低未佔分子軌道能量。我們發現縮減交互作用對於游離能和fundamental gap的影響甚大，對於原子化能量和電子親和力的影響則相對較小。除此之外，我們利用fundamental gap和Kohn-Sham gap的差距估計交換關聯能量(exchange-correlation energy)的導數不連續(derivative discontinuity)。我們發現，導數不連續會隨縮減交互作用而減少。

關鍵字

縮減庫倫薛丁格方程式；密度泛函理論；短程哈密頓算符

並列摘要

We investigate the impact of attenuated interaction on electronic properties of several molecules. In the calculation, the complementary error function, erfc(r), is used to modify the ordinary -1/r Coulombic interaction. Multiple methods are used in the calculation including CCSD(T), CCSD, MP2, Hartree-Fock, SR-LDA, and SR-PBE. The results from CCSD(T) are taken as reference values and are compared with the results from the others. For each molecule species, we calculated the atomization energy, ionization potential, electron affinity, fundamental gap, highest occupied molecular orbital (HOMO) energy, and lowest unoccupied molecular orbital (LUMO) energy. We found that this modification has huge influence on the ionization potentials and so does the fundamental gaps. The influence on the atomization energies and electron affinities are relatively small. Based on the results from Kohn-Sham method and CCSD(T), the derivative discontinuity of each entry is also estimated by calculating the difference between Kohn-Sham gap and fundamental gap. The derivative discontinuity is found to be smaller in attenuated interaction.