Composite vibrational spectroscopy of the group 12 difluorides: ZnF2, CdF2, and HgF2

Abstract

The vibrational spectra of group 12 difluorides, MF2 (M = Zn, Cd, Hg), were investigated via coupled cluster singles, doubles, and perturbative triples, CCSD(T), including core correlation, with a series of correlation consistent basis sets ranging in size from triple-zeta through quintuple-zeta quality, which were then extrapolated to the complete basis set (CBS) limit using a variety of extrapolation procedures. The explicitly correlated coupled cluster method, CCSD(T)-F12b, was employed as well. Although exhibiting quite different convergence behavior, the F12b method yielded the CBS limit estimates closely matching more computationally expensive conventional CBS extrapolations. The convergence with respect to basis set size was examined for the contributions entering into composite vibrational spectroscopy, including those from higher-order correlation accounted for through the CCSDT(Q) level of theory, second-order spin-orbit coupling effects assessed within four-component and two-component relativistic formalisms, and vibrational anharmonicity evaluated via a perturbative treatment. Overall, the composite results are in excellent agreement with available experimental values, except for the CdF2 bond-stretching frequencies compared to spectral assignments proposed in a matrix isolation infrared and Raman study of cadmium difluoride vapor species [Loewenschuss et al., J. Chem. Phys. 50, 2502 (1969); Givan and Loewenschuss, J. Chem. Phys. 72, 3809 (1980)]. These assignments are called into question in the light of the composite results.

High Valent Mercury Fluoride Ions

“…Quantum chemistry calculations show a range of HgÀ F distance 1.897-2.034 Å for HgF 2 depending upon the level of theory and basis sets. [30][31][32] The reported HgÀ F bond distances, 1.934 and 1.922 Å with B3LYP and CCSD(T) methods agree well with the Metal halide perovskites with general chemical structure ABX 3 show unique optical and electronic properties. Thus finds application in the optoelectronic devices fabrication.…”

Toward Chemical Accuracy in ab Initio Thermochemistry and Spectroscopy of Lanthanide Compounds: Assessing Core–Valence Correlation, Second-Order Spin–Orbit Coupling, and Higher Order Effects in Lanthanide Diatomics

“…4 Noteworthy, recent computational studies employing the high-level Feller−Peterson−Dixon (FPD) composite approach 4,7,8 have demonstrated the potential for achieving an accuracy in the spectroscopic properties of transition metal-containing molecules well below this threshold. 9,10 For lanthanide compounds, the accuracy that can be achieved by a composite method is still not established well enough. A recent review on the correlation consistent composite approach strategies and applications 5 states that the combination of calculations used in composite approaches allows for energetic predictions to be within 5 kcal•mol −1 for lanthanides.…”

“…The term “chemical accuracy” was applied to the results of these studies as well, with a threshold chosen (though rather arbitrarily) to be ±0.005 Å and ±15 cm –1 for the deviations in bond lengths and frequencies, respectively . Noteworthy, recent computational studies employing the high-level Feller–Peterson–Dixon (FPD) composite approach ,, have demonstrated the potential for achieving an accuracy in the spectroscopic properties of transition metal-containing molecules well below this threshold. , …”

Vaporization Processes and Accurate Molecular Structure of a Number of Organic and Inorganic Compounds Promising for Use in Technologies Involving the Gas Phase

“…С применением разработанных в нашей лаборатории методов были впервые изучены несколько десятков важных для теории и практики соединений, в том числе молекулы сульфида бария BaS [122], галогенидов таллия TlX (X = F, Cl, Br, I) [123], оксидов и галогенидов лантанидов LnX (Ln = La, Eu, Yb, Lu; X = O, F, Cl, Br, I) [124], оксидов иттрия YO [125], гадолиния GdO [126], тория и америция ThO и AmO [127], дифторидов цинка, кадмия и ртути MF2 (M = Zn, Cd, Hg) [128], дигалогенидов иттербия YbX2 (X = F, Cl, Br, I) [129]. Во всех случаях наблюдалось прекрасное согласие результатов теоретических предсказаний с имеющимися экспериментальными данными: среднее абсолютное отклонение от опыта составляло менее 0,005 Å в межъядерных расстояниях, 5 см -1 в частотах колебаний и 2-3 ккал/моль в энтальпиях атомизации соответственно.…”