Diffusion Monte Carlo Calculations for Rare-earths: Hartree-Fock, Hybrid B3LYP, and Long-range Corrected LC-BLYP Functional

Our study aim is to make highlights on the failure or success of both popular B3LYP functional and long-range corrected LC-BLYP functional at different values of the range separation parameter in improving the ground state and excited states energies calculations for 4f-lanthanides and 5f-actinides. The most popular B3LYP functional fails to provide a balanced description of excitation energies for 4f-lanthanides. However, it gives reasonable results for the actinides with exception of Pu and Am atoms. The ground state energies of 5f-actinides are improved significantly at the critical value of the range separation parameter equals 0.35 a.u. while the optimal value for the excited states lies in the critical range of 0.35-0.4 a.u. However, our results show that LC-BLYP functional is not recommended for 4f-lanthanides which have strongly localized nature.