The quantum states of normal muonium and atomic H in crystalline material were investigated by using the path integral molecular dynamics method, and interatomic potentials which were based upon density functional theory. It was shown that, in spite of instability of the potential energy surface, muonium had a high density at the center of a Si cage (T site); due to quantum effects. A more classical distribution was suggested for H.

Quantum distributions of muonium and H in crystalline silicon T.Miyake, T.Ogitsu, S.Tsuneyuki: Physical Review Letters, 1998, 81[9], 1873-6