Interactions of C ⁺ ( ² P _J ) with rare gas atoms: incipient chemical interactions, potentials and transport coefficients

Abstract

Accurate interatomic potentials were calculated for the interaction of a singly-charged carbon cation, C + , with a single rare gas atom, RG (RG = Ne-Xe). The RCCSD(T) method and basis sets of quadruple- and quintuple- quality were employed; each interaction energy is counterpoise corrected and extrapolated to the basis set limit. The lowest C + ( 2 P) electronic term of the carbon cation was considered, and the interatomic potentials calculated for the diatomic terms that arise from these: 2  and 2  + . Additionally, the interatomic potentials for the respective spin-orbit levels were calculated, and the effect on the spectroscopic parameters was examined. In doing this, anomalously large spin-orbit splittings for RG = Ar-Xe were found, and this was investigated using multireference configuration interaction (MRCI) calculations. The latter indicated a small amount of RG  C + electron transfer and this was able to rationalize the observations. This is taken as evidence of an incipient chemical interaction, which was also examined via contour plots, Birge-Sponer plots and various population analyses across the C + -RG series (RG = He-Xe), with the latter showing unexpected results. Trends in several spectroscopic parameters were examined as a function of the increasing atomic number of the RG atom. Finally, each set of RCCSD(T) potentials was employed including spin-orbit coupling to calculate transport coefficients for C + in RG, and the results compared to the limited available data.

Interactions of Si+(2PJ) and Ge+ (2PJ) with rare gas atoms (He–Rn): interaction potentials, spectroscopy, and ion transport coefficients

“…Here, we expect the parameters for the 2 Π 3/2 state to be the same as for the 2 Π state, since there are no other Ω = 3/2 states with which to interact, and this is largely the case for RG = He–Ar, but with small deviations occurring for the cases with the heavier RG, particularly for Si + –RG. Such deviations were also seen for C + –RG, 37 and are commented on later.…”

“…We hypothesise that the Mulliken analyses are misattributing the electron density, owing to the large size of the RG atom, and also the “embedding” of the cation into the region where the RG density would be expected – see ref. 37 for orbital contour plots that show this effect for C + –RG.…”

“…Similar observations were made for the C + –RG complexes (see ref. 26 and 37). The resultant equilibrium position arises from a balance of electrostatic attractive and repulsive interactions, as well as Pauli repulsion and has been discussed by Bellert and Breckenridge in ref.…”

Data Needs for Modeling Low-Temperature Non-Equilibrium Plasmas: The LXCat Project, History, Perspectives and a Tutorial

“…Data for 424 positively or negatively charged atomic and molecular ions is available for a wide variety of elements across the periodic table of elements (see also Figure 6). Some of the notable changes and extensions since 2016 in the Viehland database involve ions of C [162,163], Co, Cr, and Ni [164], Gd [165], K [166,167], Mg [168][169][170][171], O [172,173], S [174], and Si [175].…”

Modern theoretical chemistry: the legacy of Prof. John N. Murrell

“…Two papers on the topic of non-reactive collisions investigate ion transport and energy transfer. Tuttle et al [9] use accurate interatomic potentials to study the interaction between C + and a series of rare gas atoms, and provide evidence for a small chemical component to the interaction that arises from electron transfer between the constituents. Calculated transport coefficients point to the presence of a single spin-orbit component in the complementary experiments.…”