2001 Volume 34 Issue 2 Pages 207-210
In order to represent the thermal motion of a hydrogen atom and a proton trapped inside a diamond lattice, trajectories of these oscillators around the trapping site were simulated using a C26H32 cluster model on the basis of the semi-empirical PM3-MO method combined with the direct molecular orbital (MO) dynamics calculation. Trapping occurs in the tetrahedral (T) interstitial site for both the hydrogen atom and the proton. With increasing temperature from 0 to 600 K the hydrogen and proton show an increase in amplitude of vibration due to the thermal activation. The hydrogen atom vibrates only around the trapping site up to 600K, which leads to a decrease in the spin density for the atom from 0.971 at 0 K to 0.963 at 600 K. On the other hand, the proton is observed to transfer to the next tetrahedral site, exceeding the potential energy barrier at 600 K. No other trapping sites can be found in this process.