Theoretical study of the electronic structure of the low-lying states of the Li2H molecule

Results of a complete active space self-consistent field treatment of the two lowest states of each symmetry (2)A(1), B-2(1), and B-2(2) of Li2H are reported. An isosceles triangle is predicted for the equilibrium geometry of the ground state (1)(2)A(1) (R(LiLi) = 2.48 Angstrom, R(LiH) = 1.70 Angstrom) (1 Angstrom = 10(-10) m) and of the excited state (1)B-2(1) (R(LiLi) = 2.91 Angstrom, R(LiH) = 1.58 Angstrom) while a linear geometry is predicted for the (1)B-2(2), (2)(2)A(1), (2)B-2(2), and (2)B-2(1) states with the following values for R(LiH) = R(LiLi)/2 : 1.66, 1.57, 1.66, and 1.57 Angstrom, respectively. Fitted analytical forms of the potential energy surfaces for the six states investigated are also displayed.