He-He chemical bonding in high-frequency intense laser fields

On the basis of the Kramers-Henneberger (KH) high-frequency approximation, we carried out an ab initio molecular orbital calculation for He-2 in intense laser fields. The potential energy curve is found to be attractive, indicating that a He-He chemical bond is formed. The formation of the He-He chemical bond is ascribable to changes in the nature of KH molecular orbitals. Intense laser fields cause a kind of sp hybridization of KH atomic orbitals. The degree of the hybridization depends on the internuclear distance, and reaches a maximum at around the equilibrium internuclear distance. This hybridization remarkably strengthens/weakens the bonding/anti-bonding character of the 1delta(g)/1delta(u) KH molecular orbitals, respectively.