Theoretical study on low-lying states of Ga2X (X = P, As) with coupled-cluster approaches.
Theoretical study on low-lying states of Ga2X (X = P, As) with coupled-cluster approaches.
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DOI：
10.1039/c3cp52192c
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发表时间：
2013-10
期刊：
影响因子：
--
通讯作者：
Yan-Ni Liang;Fan Wang;Xiangyuan Li
中科院分区：
文献类型：
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作者：
Yan-Ni Liang;Fan Wang;Xiangyuan Li
本文采用单双能级（EOMIP-CCSD）和CCSD、CCSD（T）、DFT和CCSDT-3水平上的电离态运动方程耦合团簇方法研究了Ga 2 P和Ga 2As的低激发态。除了（2）B2和（2）A1态的非对称伸缩b2模外，所有这些方法提供的结构、频率和绝热电子亲合势彼此合理一致。根据我们的计算结果，这两个分子的最低能态是C（s）对称的（2）A'态，（2）B2态是C（2 v）对称的基态。对于b2模，CCSD和CCSD（T）为（2）B2态提供了真实的频率，而EOM方法和DFT方法得到的大多数交换相关泛函都是虚频率。（2）B2态和（2）A1态由于沿着b2模的畸变通过伪Jahn-Teller效应而彼此耦合。结果分析表明，EOM方法为两个态提供了合理的b2频率，DFT方法除了BP 86和PBE方法外，都为（2）B2态提供了定性正确的b2频率。此外，我们还引入了一个势矩阵来描述（2）B2和（2）A1态之间的电子振动耦合，并将该势矩阵中的参数拟合到由EOMIP-CCSD结果得到的绝热势曲线上。
Low-lying states of Ga2P and Ga2As are investigated with the equation-of-motion coupled-cluster approach for ionized states at the singles and doubles level (EOMIP-CCSD) as well as at the CCSDT-3 level together with CCSD, CCSD(T), and DFT. Except for the asymmetric stretching b2 mode of the (2)B2 and (2)A1 states, all these approaches provide structures, frequencies and adiabatic electron affinities that are in reasonable agreement with each other. According to our results, the lowest-energy state of these two molecules is the (2)A' state of C(s) symmetry and the (2)B2 state is the ground electronic state with C(2v) symmetry. As for the b2 mode, CCSD and CCSD(T) afford real frequencies for the (2)B2 state, while EOM approaches and DFT with most exchange-correlation functionals give rise to imaginary frequencies. The (2)B2 and (2)A1 states couple with each other due to distortion along b2 mode through the pseudo-Jahn-Teller effect. Analysis on results shows that EOM approaches afford reasonable b2 frequencies for the two states and DFT approaches, except for BP86 and PBE, provide qualitatively correct b2 frequencies for the (2)B2 state. In addition, a potential matrix is introduced to describe the vibronic coupling between the (2)B2 and (2)A1 states and parameters in the matrix are fitted to the adiabatic potential curves from EOMIP-CCSD results.