Constant temperature molecular dynamics simulations of energetic particle-solid collisions: comparison of temperature control methods

Appropriate temperature control methods must be incorporated into simulations that maintain constant temperature. A specific role played by these methods in modeling energetic particle-solid collisions is to absorb the excess energy wave generated by the collision that, if left unchecked, propagates through the material and reflects from the system boundaries. In this study, five temperature control methods are investigated for use in molecular dynamics simulations of carbon cluster deposition on diamond surfaces. These five methods are the Nose-Hoover thermostat, the generalized Langevin equation (GLEQ) approach, the Berendsen method, a modified GLEQ approach where an extra damping mechanism is introduced, and a combination of the GLEQ and Berendsen methods. The temperature control capability and the effectiveness of these methods at reducing the amplitude of the reflected energy wave produced in these systems are compared and discussed. It is found that the realistic performance of these methods depends on the specifics of the system, including incident energy and substrate size. Among the five methods considered, the Berendsen method is found to be effective at removing excess energy in the early stages of the deposition process, but the resultant final temperatures are relatively high in most cases. Additionally, the performance of the Nose-Hoover thermostat is similar to that of the Berendsen method. If the diamond substrate is large enough and the incident energy is not too high, the GLEQ approach is found to be sufficient for removal of excess energy. However, the modified GLEQ approach and the Dew, combined thermostat perform moderately better than the other approaches at high incident energies. (C) 2004 Elsevier Inc. All rights reserved.