Calculation of transition frequencies forH2+and its isotopes to spectroscopic accuracy

Abstract

Calculations are reported of certain low-lying infrared transition frequencies in ${\mathrm{H}}_2^{+}$, ${\mathrm{D}}_2^{+}$, H${\mathrm{D}}^{+}$, H${\mathrm{T}}^{+}$, and D${\mathrm{T}}^{+}$. They take account of radiative, relativistic, and nonadiabatic effects and are made to the same level of accuracy (0.002 ${\mathrm{cm}}^{-1\mathrm{}}$) as the recent experimental measurements for H${\mathrm{D}}^{+}$; for the (1,0-0,1), (1,1-0,2), and (2,1-1,0) transitions for this molecular ion, the frequencies are 1869.135 (1869.134), 1823.534 (1823.533), and 1856.781 (1856.778) ${\mathrm{cm}}^{-1\mathrm{}}$, where the experimental results are shown in parentheses. We predict that the current values of the mass ratios $\frac{m_e}{m_p}$ and $\frac{m_e}{m_d}$ are good to ±2 in the sixth significant figure. The nonadiabatic energies are based on extremely large basis sets (up to and including 515 basis functions) and required special techniques for solving the generalized eigenvalue equation.