Department of Physics, North Carolina State University, Raleigh, North Carolina 27695-8202, USA.
Sandia National Laboratories, Albuquerque, New Mexico 87123, USA.
J Chem Phys. 2018 Sep 14;149(10):104108. doi: 10.1063/1.5038135.
Very recently, we have introduced correlation consistent effective core potentials (ccECPs) derived from many-body approaches with the main target being their use in explicitly correlated methods, while still usable in mainstream approaches. The ccECPs are based on reproducing excitation energies for a subset of valence states, namely, achieving near-isospectrality between the original and pseudo Hamiltonians. In addition, binding curves of dimer molecules were used for refinement and overall improvement of transferability over a range of bond lengths. Here we apply similar ideas to the 2nd row elements and study several aspects of the constructions in order to find the high accuracy solutions within the chosen ccECP forms with 3, 3 valence space (Ne-core). Our new constructions exhibit accurate low-lying atomic excitations and equilibrium molecular bonds (on average within ≈0.03 eV and 3 mÅ); however, the errors for Al and Si oxide molecules at short bond lengths are notably larger for both ours and existing effective core potentials. Assuming this limitation, our ccECPs show a systematic balance between the criteria of atomic spectra accuracy and transferability for molecular bonds. In order to provide another option with much higher uniform accuracy, we also construct He-core ccECPs for the whole 2nd row with typical discrepancies of ≈0.01 eV or smaller.
最近，我们引入了基于多体理论的相关一致有效核势（ccECPs），主要目标是将其应用于显式相关方法中，同时仍可用于主流方法。ccECPs 基于再现一组价态的激发能，即实现原始和赝 Hamilton 之间的近等谱性。此外，二聚体分子的结合曲线被用于改进和提高在一系列键长范围内的转移能力。在这里，我们将类似的想法应用于第二周期元素，并研究了构建的几个方面，以便在所选的 3、3 价空间（Ne 核）的 ccECP 形式内找到高精度的解。我们的新构造表现出准确的低能原子激发和平衡分子键（平均在 ≈0.03 eV 和 3 mÅ 内）；然而，对于我们和现有的有效核势，Al 和 Si 氧化物分子在短键长下的误差明显更大。假设这种限制，我们的 ccECPs 在原子光谱精度和分子键转移能力的标准之间表现出系统的平衡。为了提供另一种具有更高均匀精度的选择，我们还为整个第二周期构建了 He 核 ccECPs，其典型差异约为 ≈0.01 eV 或更小。
