Franck–Condon simulation of the photoelectron spectrum of AsCl₂ and the photodetachment spectrum of AsCl employing UCCSD(T)‐F12a potential energy functions: IE and EA of AsCl₂

Abstract

The currently most reliable theoretical estimates of the adiabatic ionization energies (AIE(0)) from the X̃(2)B(1) state of AsCl(2) to the X̃(1)A(1) and ã(3)B(1) states of AsCl 2+, and the electron affinity (EA(0)) of AsCl(2) , including ΔZPE corrections, are calculated as 8.687(11), 11.320(23), and 1.845(12) eV, respectively (estimated uncertainties based on basis-set effects at the RCCSD(T) level). State-of-the-art ab initio calculations, which include RCCSD(T), CASSCF/MRCI, and explicitly correlated RHF/UCCSD(T)-F12x (x = a or b) calculations with basis sets of up to quintuple-zeta quality, have been carried out on the X̃(2)B(1) state of AsCl(2) , the X̃(1)A(1) , ã(3)B(1) , and Ã(1)B(1) states of AsCl 2+, and the X̃(1)A(1) state of AsCl 2-. Relativistic, core correlation and complete basis-set (CBS) effects have been considered. In addition, computed UCCSD(T)-F12a potential energy functions of relevant electronic states of AsCl(2) , AsCl (2)(+), and AsCl( 2)(-) were used to calculate Franck-Condon factors, which were then used to simulate the valence photoelectron spectrum of AsCl(2) and the photodetachment spectrum of AsCl (2)(-), both yet to be recorded. Lastly, we have also computed the AIE and EA values for NCl(2) , PCl(2) , and AsCl(2) at the G4 level and for SbCl(2) at the RCCSD(T)/CBS level. The trends in the AIE and EA values of the group V pnictogen dichlorides, PnCl(2) , where Pn = N, P, As, and Sb, were examined. The AIE and EA of PCl(2) were found to be smaller than those of AsCl(2) , contrary to the order expected from the IE values of P and As.

Franck-Condon simulation, including anharmonicity, of the photodetachment spectrum of P2H−: Restricted-spin coupled-cluster single-double plus perturbative triple and unrestricted-spin coupled-cluster single-double plus perturbative triple -F12x potential energy functions of P2H and P2H−

“…Employing the computed FCFs, we find that simulated photodetachment spectra obtained using these RCCSD(T) and UCCSD(T)-F12x PEFs are almost identical. This once again supports our previous conclusion [11][12][13] that the explicitly correlated method, UCCSD(T)-F12x, could be used to generate reliable PEFs in lieu of conventional correlated methods, such as RCCSD(T), at a considerably reduced cost. In addition, we have reported computed fundamental vibrational frequencies for P 2 H and P 2 H − for the first time, and these computed frequencies agree very well with available experimental values from the photodetachment spectrum of P 2 H − .…”

“…The use of the UCCSD(T)-F12x method follows our recently published works on AsX 2 (X = H, F, or Cl), and their ions, [11][12][13] where Franck-Condon spectral simulations including allowance for anharmonicity were carried out on theÃ(0,0,0)-X SVL emission spectrum of AsH 2 , 11 the photoelectron spectra of AsF 2 and AsCl 2 , and the photodetachment spectra of AsF 2 − and AsCl 2 − , 12, 13 using UCCSD(T)-F12x potential energy functions (PEFs). In these studies, [11][12][13] it was concluded that the explicitly correlated method, UCCSD(T)-F12x, could be used to generate reliable PEFs in lieu of conventional correlated methods, such as RCCSD(T), at a considerably reduced cost. Specifically, simulated spectra obtained using RCCSD(T)/aug-cc-pCV5Z and RHF/UCCSD(T)-F12a/aug-cc-pCVTZ PEFs are essentially identical (see Refs.…”

The enthalpies of formation of AsXn molecules, where X = H, F or Cl, and n = 1, 2 or 3, by RCCSD(T) and UCCSD(T)-F12x calculations

“…Recently, we have published high level ab initio calculations on AsX 2 , where X = H, F or Cl, and their ions. [1][2][3] In these studies, Franck-Condon spectral simulations were carried out on the A ˜(0,0,0)-X ˜SVL emission spectrum of AsH 2 , 1 the photoelectron spectra of AsF 2 and AsCl 2 , and the photodetachment spectra of AsF 2 À and AsCl 2 À . 2,3 In addition, the currently most reliable calculated values of the ionization energies and electron affinities of AsF 2 and AsCl 2 were reported.…”

“…[1][2][3] In these studies, Franck-Condon spectral simulations were carried out on the A ˜(0,0,0)-X ˜SVL emission spectrum of AsH 2 , 1 the photoelectron spectra of AsF 2 and AsCl 2 , and the photodetachment spectra of AsF 2 À and AsCl 2 À . 2,3 In addition, the currently most reliable calculated values of the ionization energies and electron affinities of AsF 2 and AsCl 2 were reported. 2,3 In the course of these investigations, [1][2][3] it has come to our attention that, for some simple arsenic hydrides and halides, which are of particular importance in the microelectronics industry, 4 as well as in many other areas (e.g.…”

“…2,3 In addition, the currently most reliable calculated values of the ionization energies and electron affinities of AsF 2 and AsCl 2 were reported. 2,3 In the course of these investigations, [1][2][3] it has come to our attention that, for some simple arsenic hydrides and halides, which are of particular importance in the microelectronics industry, 4 as well as in many other areas (e.g. pigments, insecticides, herbicides, antiseptics, drugs and explosives), 5,6 some of their thermodynamic key quantities, such as, enthalpies of formation (DH f Ø ), appear to be not well established.…”