Tenorio Bruno Nunes Cabral, Moitra Torsha, Nascimento Marco Antonio Chaer, Rocha Alexandre Braga, Coriani Sonia
Instituto de Química, Universidade Federal do Rio de Janeiro, UFRJ, Av. Athos da Silveira Ramos, 149, Rio de Janeiro, RJ 21941-909, Brazil.
DTU Chemistry, Technical University of Denmark, Kemitorvet, Building 207, DK-2800 Kongens Lyngby, Denmark.
J Chem Phys. 2019 Jun 14;150(22):224104. doi: 10.1063/1.5096777.
Oxygen, nitrogen, and carbon K-shell photoabsorption and photoionization cross sections have been calculated within core-valence-separated coupled cluster (CC) linear response theory for a number of molecular systems, namely, water, ammonia, ethylene, carbon dioxide, acetaldehyde, furan, and pyrrole. The cross sections below and above the K-edge core ionization thresholds were obtained, on the same footing, from L basis set calculations of the discrete electronic pseudospectrum yielded by an asymmetric-Lanczos-based formulation of CC linear response theory at the CC singles and doubles (CCSD) and CC singles and approximate doubles (CC2) levels. An analytic continuation procedure for both discrete and continuum cross sections as well as a Stieltjes imaging procedure for the photoionization cross section were applied and the results critically compared.
利用核价分离耦合簇（CC）线性响应理论，对多个分子体系，即水、氨、乙烯、二氧化碳、乙醛、呋喃和吡咯，计算了氧、氮和碳的K壳层光吸收和光电离截面。在相同基础上，通过基于非对称兰索斯的CC线性响应理论公式，在CC单双激发（CCSD）和CC单激发与近似双激发（CC2）水平下，从L基组计算离散电子赝谱，得到了K边核心电离阈值上下的截面。应用了离散和连续截面的解析延拓程序以及光电离截面的斯蒂尔杰斯成像程序，并对结果进行了严格比较。
