Energy barrier to reorientation of the substitutional nitrogen in diamond

A first-principles method using the local spin-density approximation to density-functional theory is used to investigate the neutral substitutional nitrogen atom in diamond. The length of the unique extended nitrogen-carbon bond in the C₃ᵥ symmetry equilibrium structure is found to be 33% longer than the bulk diamond bond length. The energy barrier to the reorientation of this extended bond between the four possible nitrogen-carbon bonds is determined to be 0.7 eV, in excellent agreement with experimental estimates. {} 1996 The American Physical Society.