H2 ion in a strong magnetic field: Lowest gerade and ungerade electronic states

In framework of variational method with a single trial function an accurate study of the lowest gerade 1g and ungerade 1u electronic states of the molecular ion H 2 in a magnetic field ranging 0− 4.414× 10 13 G for an arbitrary orientation angle of the molecular axis 0 ≤ θ ≤ 90 is performed. Oneparametric gauge dependence in the Hamiltonian is introduced then variationally optimized. A well pronounced minimum on the total energy surface of the (ppe) system in both 1g and 1u states is found for all studied magnetic fields and all orientations. The parallel configuration (θ = 0) at equilibrium has minimal total energy for both states. It is found that for given θ for both states the magnetic field growth is always accompanied by binding energy increase and shrinking of the equilibrium distance. We demonstrate that for B & 1.8 · 10 G the molecular ion can dissociate to H 2 → H + p over a certain range of orientations (θcr ≤ θ ≤ 90 ), where the minimal θcr ≃ 25 ◦ occurs for the strongest magnetic field studied, B = 4.414 · 10 G. For B < 10 G the ion H 2 in 1g, 1u states is the most bounded when in perpendicular configuration (θ=90), whereas for B & 10 this occurs for an angle < 90. For 1g state in any orientation with the magnetic field growth two-peak electronic distribution changes to single-peak one at B ∼ 10 G. On leave of absence from the Institute for Theoretical and Experimental Physics, Moscow 117259, Russia.