EXCITATION AND ELECTRON TRANSFER IN H(1s)-H(1s) COLLISIONS. Junbai Wang*, Jan Petter Hansen* and Alain Dubois$ * Department of Physics, University of Bergen, Norway. $ Laboratoire de Chimie Physique-Matiere et Rayonnement, Universite Pierre et Marie Curie, Paris, France. We have studied the H(1s)-H(1s) collision system using a semiclassical close-coupling approach involving extended atomic-state basis sets. During the conference cross sections for excitation, double excitation and electron transfer will be presented in the 1-100 keV/amu impact energy range.