Accuracy of a random-walk-based approach in the determination of equilibrium bond lengths and harmonic frequencies for some doublet first-row diatomic radicals

The accuracy of equilibrium bond lengths and harmonic frequencies for 12 doublet first-row diatomic radicals is presented as predicted by the fixed-node diffusion quantum Monte Carlo method based on the Ornstein-Uhlenbeck random walk guided by the floating spherical Gaussian orbital and spherical Gaussian geminal-type trial wave function. Compared to the experimental determined values, the random-walk-based approach gives the absolute mean deviations of 0.0019 A and 18 cm-1 for the equilibrium bond length and harmonic frequency, respectively. We also compare the random-walk-based results with some coupled-cluster-based values.