The ab initio calculation for Li2F and Na2F systems

The globally accurate potential energy surface for the ground state of Li2F and Na2F systems was presented using the coupled-cluster singles and doubles excitation approach with perturbation treatment of triple excitations. Mixed basis sets were applied, aug-cc-pCVQZ for the lithium and sodium atoms and aug-cc-pCVDZ for the fluoride atom, with midbond functions (3s3p2d). In total, about 2080 points were generated for three-dimensional surfaces. Both the Li2F and Na2F molecules were confirmed to be bent at equilibrium. For Li-F-Li with an angle of 90 degrees, the depth of the potential well is 3.87 eV at R = 2a(0,) and the height of the barrier required to linearity with 0 degrees angle equals 285.76 eV at R = 5.6a(0). For Na-F-Na with an angle of 90 degrees, the depth of the potential well is 5.289 eV at R = 3a(0), and the height of the barrier required to linearity with 0 degrees angle equals 721 eV at R = 2.6a(0). Our ab initio calculations of potential surface and potential energy surface were compared with the experimental results.