Contour plot of the symmetry unique fragment of the He–H2 two-body potential energy surface as a function of (R, θ) for r HH = 1.448736 bohrs. The energy unit is 1 K.
The He–H2 interaction second virial coefficient as a function of temperature. The results with our 2D potential and with the original BMP 14 and BMPmod potentials (truncated to r HH = 1.448736 bohrs) are presented. The experimental data are taken from Refs. 97 (x), 98 (circles), and 96 (diamonds).
Two-body interaction energy contributions (in Kelvin) for the near-minimum geometry (r HH, R, θ) = (1.448736 bohrs, 6.4 bohrs, 0°) computed using different basis sets. The columns marked “extr.” contain CBS-extrapolated contributions, with the value in the X row obtained using basis sets with cardinal numbers X − 1 and X. The values at the level used to compute all 1900 ab initio data points are marked in bold. The CCSD(T) calculations for the da5Z+(da5Z) and da7Z+(da7Z) bases failed to converge.
Two-body interaction energy contributions (in Kelvin) for the near-saddle point geometry (r HH, R, θ) = (1.448736 bohrs, 6.3 bohrs, 90°) computed using different basis sets. The columns marked “extr.” contain CBS-extrapolated contributions, with the value in the X row obtained using basis sets with cardinal numbers X − 1 and X. The values at the level used to compute all 1900 ab initio data points are marked in bold.
The diagonal Born-Oppenheimer correction to the He–H2 interaction energy (in Kelvin) for the near-minimum and near-saddle point geometries computed using different basis sets.
Parameters of the 2D and 3D potentials V(R, θ) and V(r HH, R, θ) (Eqs. (7) and (3) , respectively) fitted to the accurate two-body He–H2 interaction energies computed in this work. The units of all parameters are such that Eqs. (7) and (3) give the potential in Kelvin when R and r HH are in bohr. 39 Not all digits listed are significant: the extra digits are given for consistency with the programmed expressions. In the lower part of the table, the values of the asymptotic constants C nkl are repeated in atomic units (hartree bohr n ) to facilitate comparisons with literature.
Statistical measures of the accuracy of the original BMP 14 and BMPmod potentials with respect to different ab initio results. The upper part of the table pertains to total binding energies V tot = E int, 2B + V H-H (where the last term, the binding energy of the H2 molecule, is computed using the potential of Schwenke 46 ), and lists the full-weighted RMSE and energy-only-weighted RMSE (in millihartree) in accordance with Table II of Ref. 14 . The lower part of the table shows mean unsigned errors (MUE), mean unsigned relative errors (MURE), and mean unsigned errors relative to the uncertainty (MUEσ) for the E int, 2B term alone using different sets of data in the vdW He–H2 region. For this part, the accuracy of our 3D potential, fitted to the ab initio data computed in this work, is shown for comparison.
Properties of the lone bound state of 4He–H2 and 3He–H2: the energy E and the average distance ⟨R⟩ and , 39 computed in this work and in previous studies. Our calculations employing the BMP and BMPmod potentials were restricted to 2D by setting r HH = 1.448736 bohrs.
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