Departamento de Física y Química Teórica, DEPg, Facultad de Química, Universidad Nacional Autónoma de México, C.P. 04510, México DF, México.
J Phys Chem A. 2012 Mar 1;116(8):1906-13. doi: 10.1021/jp2117533. Epub 2012 Feb 17.
The interactions of the iron monocation with water molecules and argon atoms in the gas phase were studied computationally to elucidate recent infrared vibrational spectroscopy on this system. These calculations employ first-principles all-electron methods performed with B3LYP/DZVP density functional theory. The ground state of Fe(+)(H(2)O) is found to be a quartet (M = 2S + 1 = 4, S is the total spin). Different binding sites for the addition of one or two argon atoms produce several low-lying states of different geometry and multiplicity in a relatively small energy range for Fe(+)(H(2)O)-Ar(2) and Fe(+)(H(2)O)(2)-Ar. In both species, quartet states are lowest in energy, and sextets and doublets lie at higher energies from the respective ground states. These results are consistent with the conclusion that the experimentally determined infrared photodissociation spectra (IRPD) of Fe(+)(H(2)O)-Ar(2) and Fe(+)(H(2)O)(2)-Ar are complicated because of the presence of multiple isomeric structures. The estimated IR bands for the symmetric and asymmetric O-H stretches from different isomers provide new insight into the observed IRPD spectra.
采用 B3LYP/DZVP 密度泛函理论的第一性原理全电子方法，对铁一价阳离子与气相水分子和氩原子的相互作用进行了计算研究，以阐明该体系近期的红外振动光谱。研究发现，Fe(+)(H(2)O)的基态为四重态（M = 2S + 1 = 4，S 是总自旋）。在 Fe(+)(H(2)O)-Ar(2)和 Fe(+)(H(2)O)(2)-Ar 中，一个或两个氩原子添加到不同的结合位点会产生几种具有不同几何形状和多重性的低能态。在这两种物质中，四重态的能量最低，六重态和双重态的能量比各自的基态高。这些结果与实验确定的 Fe(+)(H(2)O)-Ar(2)和 Fe(+)(H(2)O)(2)-Ar 的红外光解光谱（IRPD）的结论一致，即由于存在多种异构结构，因此实验确定的红外光解光谱（IRPD）非常复杂。不同异构体的对称和不对称 O-H 伸缩的估计 IR 带为观察到的 IRPD 光谱提供了新的见解。
