Estimating the intrinsic limit of the Feller-Peterson-Dixon composite approach when applied to adiabatic ionization potentials in atoms and small molecules.
Estimating the intrinsic limit of the Feller-Peterson-Dixon composite approach when applied to adiabatic ionization potentials in atoms and small molecules.
复制标题
估计 Feller-Peterson-Dixon 复合方法应用于原子和小分子的绝热电离势时的内在极限。
DOI：
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发表时间：
2017
影响因子：
4.4
通讯作者：
D. Feller
中科院分区：
文献类型：
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作者：
D. Feller
用Feller-Peterson-狄克逊（FPD）理论方法对48个原子和小分子的集合获得了基准绝热电离势。在以前的研究中，FPD方法证明了在±1 kcal/mol的95%置信水平内预测原子化能（生成热）和电子亲合能的能力。对于CCSD（T）的起始点计算，选择了包含相关一致基组的大的单粒子展开（在许多情况下可达aug-cc-pV 8 Z，某些原子可达aug-cc-pV 9 Z）。尽管它们的成本，选择这些大的基组，以帮助最大限度地减少残余基组截断误差，并减少对近似基组极限外推公式的依赖。补充的n粒子展开包括高阶CCSDT、CCSDTQ或CCSDTQ 5（具有迭代三重、四重和五重激发的耦合簇理论）校正。对于这里检查的所有化学系统，也可以进行显式全构型相互作用（CI）计算或以其他方式估计全CI极限。此外，与核心/价相关的修正，标量相对论，非谐零点振动能，非绝热效应，和其他次要因素被认为是。相对于实验的电离势的均方根偏差为0.21 kcal/mol（0.009 eV）。相应的形成的分子量的协议水平为0.37千卡/摩尔和电子亲和势0.20千卡/摩尔。在分子结构和谐波频率的情况下，发现与实验类似的良好协议。总的来说，能量，结构和振动数据（655比较）的组合反映了FPD方法的一致能力，以实现密切的协议与实验的小分子使用本研究中应用的理论水平。
Benchmark adiabatic ionization potentials were obtained with the Feller-Peterson-Dixon (FPD) theoretical method for a collection of 48 atoms and small molecules. In previous studies, the FPD method demonstrated an ability to predict atomization energies (heats of formation) and electron affinities well within a 95% confidence level of ±1 kcal/mol. Large 1-particle expansions involving correlation consistent basis sets (up to aug-cc-pV8Z in many cases and aug-cc-pV9Z for some atoms) were chosen for the valence CCSD(T) starting point calculations. Despite their cost, these large basis sets were chosen in order to help minimize the residual basis set truncation error and reduce dependence on approximate basis set limit extrapolation formulas. The complementary n-particle expansion included higher order CCSDT, CCSDTQ, or CCSDTQ5 (coupled cluster theory with iterative triple, quadruple, and quintuple excitations) corrections. For all of the chemical systems examined here, it was also possible to either perform explicit full configuration interaction (CI) calculations or to otherwise estimate the full CI limit. Additionally, corrections associated with core/valence correlation, scalar relativity, anharmonic zero point vibrational energies, non-adiabatic effects, and other minor factors were considered. The root mean square deviation with respect to experiment for the ionization potentials was 0.21 kcal/mol (0.009 eV). The corresponding level of agreement for molecular enthalpies of formation was 0.37 kcal/mol and for electron affinities 0.20 kcal/mol. Similar good agreement with experiment was found in the case of molecular structures and harmonic frequencies. Overall, the combination of energetic, structural, and vibrational data (655 comparisons) reflects the consistent ability of the FPD method to achieve close agreement with experiment for small molecules using the level of theory applied in this study.