Paracyanogen-like structures in high-density amorphous carbon nitride

An ab initio based tight-binding molecular-dynamics method is used to gener ate 60 amorphous carbon nitride structures, a-CN, with various stoichiometr ies and densities, providing the first atomic level insight into the chemic al bonding properties of these materials. Focusing on high densities, we ob serve clear trends counteracting the formation of a low-compressibilty phas e: (i) N-incorporation strongly catalyzes C-undercoordination, which in tur n (ii) causes the nitrogens to develop paracyanogen-like (CN-double and -tr iple) bonding. (iii) The most favorable densities for a-CN occur to be much lower than the desired hard crystalline ones. (C) 1999 Published by Elsevi er Science Ltd. All rights reserved.