On dipole moments of overlapping atoms. Application to H in 1 s, 2 s, and 2po states

Abstract

The dipole moments of two overlapping H atoms in the dissimilar states 1 s, 2 s and 2p$_{o}$ were calculated for both the triplet (destructive overlap) and the singlet (constructive overlap) states at large separations. The results are based on the Heitler-London method, using elliptical coordinates with the nucleus of the larger, more diffused orbital, located at a on the Z-axis of the coordinate system, and the nucleus of the smaller, less diffused orbital, located at b on the Z-axis. The origin of the coordinate system is midway between a and b. We find it instructive to identify three types of moments - a moment associated with the orbital on a, a moment associated with the orbital on b, and the overall moment, which is the sum of these two. It is shown that in the region of small overlap the calculated values of the dipoles on a and on b point towards each other in the triplet state, and away from each other in the singlet state. In every case, the total or net dipole moment points from the more diffused orbital towards the more compact orbital. The absolute value of the more diffused orbital is always found to be greater than of the more rigid orbital.