Thermal activation of the trapped proton in diamond crystal: direct molecular dynamics calculation

For simulation of thermal behavior of the proton in the tetrahedral (T) tra pping site of a C26H32 diamond cluster model, a direct molecular dynamics c alculation was accomplished in a temperature range from 100 to 800 K based on the newly developed methodology at the PM3 molecular orbital (MO) level. The proton vibrating around only the T site below 550 K, diffuses to the n ext T site through the hexagonal (H) site in low electron density region at 600 K. However, at 800 K the proton transfers through the H site to the bo nd center (BC) site and the middle (M) site designated as a middle point be tween two neighboring centers of the rhombuses composed of three carbon ato ms and the T site on the same level for each. The proton-carbon bond format ion (C-H+-C) is occurred at the M site followed by decrease in the potentia l energy. Finally, the proton is vibrating between the M site and the BC si te in high electron density region. (C) 2000 Elsevier Science B.V. All righ ts reserved.