title: Elastic constants of diamond from molecular dynamics simulations.
abstract: The elastic constants of diamond between 100 and 1100 K have been calculated for the first time using molecular dynamics and the second-generation, reactive empirical bond-order potential (REBO). This version of the REBO potential was used because it was redesigned to be able to model the elastic properties of diamond and graphite at 0 K while maintaining its original capabilities. The independent elastic constants of diamond, C(11), C(12), and C(44), and the bulk modulus were all calculated as a function of temperature, and the results from the three different methods are in excellent agreement. By extrapolating the elastic constant data to 0 K, it is clear that the values obtained here agree with the previously calculated 0 K elastic constants. Because the second-generation REBO potential was fit to obtain better solid-state force constants for diamond and graphite, the agreement with the 0 K elastic constants is not surprising. In addition, the functional form of the second-generation REBO potential is able to qualitatively model the functional dependence of the elastic constants and bulk modulus of diamond at non-zero temperatures. In contrast, reactive potentials based on other functional forms do not reproduce the correct temperature dependence of the elastic constants. The second-generation REBO potential also correctly predicts that diamond has a negative Cauchy pressure in the temperature range examined.
authors.affiliation: Department of Chemistry, United States Naval Academy, Annapolis, MD 21402, USA.
authors.forename: Guangtu
authors.initials: G
authors.lastname: Gao
authors.forename: Kevin
authors.initials: K
authors.lastname: Van Workum
authors.forename: J
authors.initials: J
authors.lastname: David Schall
authors.forename: Judith A
authors.initials: JA
authors.lastname: Harrison