DIPOLE-DIPOLE INTERACTION OF 2 EXCITED HYDROGEN-ATOMS

The interaction of two excited hydrogen atoms at large separations R i s governed by the dipole-dipole term (congruent-to R-3). The potential -curve asymptotes are obtained by diagonalizing the dipole-dipole-inte raction operator in the subspace of the degenerate unperturbed states. The symmetry properties are used for the reduction of the matrix size . In some special cases the eigenvalues are found analytically. For th e interaction of highly excited atoms an approximate semiclassical qua ntization procedure is developed. The problem is reformulated via the three-dimensional three-term recursion relations. The discrete (index) variables are converted into continuous variables and approximate (ad iabatic-type) separation of variables is achieved. This makes the prob lem effectively one dimensional and provides a qualitative interpretat ion of the spectrum structure. The simplest explicit expression for th e spectrum is obtained by using the harmonic approximation in the inde x space. It applies for the extreme eigenvalues.