Gaussian functions in Hylleraas-configuration interaction calculations. V. An accurate a b i n i t i o H+3 potential-energy surface

Abstract

Accurate a b i n i t i o potential energy computations for the H4 system: Tests of some analytic potential energy surfaces J. Chem. Phys. 95, 4331 (1991); 10.1063/1.461757 Gaussian functions in Hylleraasconfiguration interaction calculations: Potential curves for the e 3∑+ u and the f 3∑+ u states of hydrogen J. Chem. Phys. 92, 4941 (1990); 10.1063/1.457711 Potentialenergy surfaces for Pt2+H and Pt+H interactions J. Chem. Phys. 92, 541 (1990); 10.1063/1.458457 Gaussian functions in Hylleraasconfiguration interaction calculations. II. Potential curves for the b 3Σ+ u and the e 3Σ+ u states of hydrogenThe near-equilibrium potential-energy surface of the 'A ; ground state ofH3+ has been calculated at 69 different points with the Hylleraas-configuration interaction method using 13s3pld Cartesian Gaussian basis functions. This new surface is found to be substantially lower in absolute energy than all previous surface calculations. The equilibrium energy of the H3+ molecule has also been calculated with a larger 13s5p3d basis set. The minimum energy was found to be E = -1.343 827 9 hartrees at an internuclear distance of R = 1.6500 bohrs in the equilateral triangle configuration. This energy is significantly ( > 70 cm -I) lower than the previous best published variational calculation and is outside and below the error bars of the latest quantum Monte Carlo calculation. In addition, a medium-sized basis set of 13s4p2d orbitals was used to predict that the equilibrium separation is R = 1.6499 bohrs.

Ground State of the H3+ Molecular Ion: Physics Behind

“…In above CI calculations no explicit correlation was included. The trial function (16) larger number of configurations is included, see [37]- [38]. In general, the 14-parametric trial function (16) gives the eighth best result among known in literature so far (see Table III) being incomparably simpler with respect to all known trial functions.…”

Classical Dynamics of Laser-DrivenD3+

“…This minimum energy agrees with the QM BO energy QM 0 ¼ À1:34 a:u: at the QM equilibrium nuclear geometry of an equilateral triangle with nuclear separation 1.65 a.u. [32].…”

Why Hylleraas-type functions failed to predict the existence of PsLi+ and2,3PsHe+?

“…In the LCG calculations, the error of the cusp exceeds 60% for both systems and the values of δ 12 are about 3 times smaller than those computed with the ECG functions. For the Hy-CI functions the errors of ν 12 are reduced to about 30% and the values of δ 12 are about 15 times too small. Surprisingly, these errors are common to both systems, although the energy was much more accurate for Z = 0.9.…”