Article
FranckCondon Simulation of the Photoelectron Spectrum of AsCl2 and the Photodetachment Spectrum of AsCl2 Employing UCCSD(T)F12a Potential Energy Functions: IE and EA of AsCl2
Journal of Computational Chemistry
(Impact Factor: 3.6).
06/2011;
32(8):1648  1660.
DOI: 10.1002/jcc.21743

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ABSTRACT: Geometry optimization and harmonic vibrational frequency calculations have been carried out on the X̃(2)A(') state of P(2)H and the X̃(1)A(') state of P(2)H() using the restrictedspin coupledcluster singledouble plus perturbative triple excitation [RCCSD(T)] and explicitly correlated unrestrictedspin coupledcluster singledouble plus perturbative triple excitation [UCCSD(T)F12x] methods. For RCCSD(T) calculations, basis sets of up to the augmented correlationconsistent polarized valence quintuplezeta (augccpV5Z) quality were employed, and contributions from extrapolation to the complete basis set limit and from core correlation of the P 2s(2)2p(6) electrons were also included. For UCCSD(T)F12x calculations, different atomic orbital basis sets of triplezeta quality with different associated complementary auxiliary basis sets and different geminal Slater exponents were used. When the P 2s(2)2p(6) core electrons were correlated in these F12x calculations, appropriate corevalence basis sets were employed. In addition, potential energy functions (PEFs) of the X̃(2)A(') state of P(2)H and the X̃(1)A(') state of P(2)H() were computed at different RCCSD(T) and UCCSD(T)F12x levels, and were used in variational calculations of anharmonic vibrational wavefunctions, which were then utilized to calculate FranckCondon factors (FCFs) between these two states, employing a method which includes allowance for anharmonicity and Duschinsky rotation. The photodetachment spectrum of P(2)H() was then simulated using the computed FCFs. Simulated spectra obtained using the RCCSD(T)/augccpV5Z and UCCSD(T)F12x(x = a or b)/augccpCVTZ PEFs are compared and found to be essentially identical. Based on the computed FCFs, a more detailed assignment of the observed vibrational structure than previously reported, which includes "hot bands," has been proposed. Comparison between simulated and available experimental spectra has been made, and the currently most reliable sets of equilibrium geometrical parameters for P(2)H and its anion have been derived. The photodetachment spectrum of P(2)D, yet to be recorded, has also been simulated.The Journal of Chemical Physics 09/2011; 135(12):124312. DOI:10.1063/1.3640037 · 3.12 Impact Factor 
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ABSTRACT: RCCSD(T) and UCCSD(T)F12x calculations were performed on AsX(n) molecules, where X = H, F or Cl, and n = 1, 2 or 3, and related species, in order to evaluate their enthalpies of formation (ΔH(f)(Ø)). The recommended ΔH(f)(Ø) values obtained from the present investigation are AsH, 57.7(2); AsF, 7.9(3); AsCl, 27.2(4); AsH(2), 39.8(4); AsF(2), 96.6(9); AsCl(2), 17.8(10); AsH(3), 17.1(4); AsF(3)196.0(5) and AsCl(3), 59.1(27) kcal mole(1). These values are anchored only on one thermodynamic quantity, namely, ΔH(f)(Ø)(As) (= 70.3 kcal mole(1)). In the calculations, the fullyrelativistic smallcore effective core potential (ECP10MDF) was used for As. Contributions from outer core correlation of As 3d(10) electrons were computed explicitly in both RCCSD(T) and UCCSD(T)F12 calculations with additional tight basis functions designed for As 3d(10) electrons. Basis sets of up to augmented correlationconsistent polarized valence quintuplezeta (augccpV5Z) quality were used in RCCSD(T) calculations and computed relative electronic energies were extrapolated to the complete basis set (CBS) limit. For the simplified, explicitly correlated UCCSD(T)F12x calculations, basis sets of up to quadruplezeta (QZ) quality were employed. Based on the RCCSD(T)/CBS benchmark values, the reliability of available theoretical and experimental values have been assessed.Physical Chemistry Chemical Physics 05/2011; 13(20):954053. DOI:10.1039/c1cp20490d · 4.20 Impact Factor
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