ON THE EFFECT OF QUENCH RATE ON THE STRUCTURE OF AMORPHOUS-CARBON

We have simulated, via tight binding molecular dynamics (TBMD), the pr ocess of the quench from a melt of an atomic scale system of carbon. W e have correlated the local properties of the resulting structure to t he quench rate used to bring the liquid phase beyond the glass transit ion temperature. Results have been analyzed also in terms of the hamil tonian model used to describe the simulated system. In this respect, a morphous structures generated via tight binding and ab initio molecula r dynamics have been compared. Results indicate that quench rates as s low as 10(14) K/s produce the onset of an increasingly high fraction o f threefold coordinated sites in the structure. Moreover, it has been put in evidence the tendency of the tight binding approach to favor th reefold coordinated sites with respect to fourfold coordinated, even i n the fast quench rates domain. Copyright (C) 1998 Elsevier Science B. V.