Eur. Phys. J. B 84, 1-9 (2011)
https://doi.org/10.1140/epjb/e2011-20370-0

Regular Article

Effect of lattice relaxation on spin density of nitrogen-vacancy centers in diamond and oscillator strength calculations

¹ Department of Physics, Sharif University of Technology, P.O. Box: 11365-9161, Tehran, Iran
² Physics Group, Maleke ashtar University of Technology, P.O. Box: 83145-115, Shahin Shahr, Iran
³ Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan

^a e-mail: heydaris@yahoo.com

Received: 14 May 2011
Received in final form: 13 July 2011
Published online: 3 November 2011

Abstract

Using a generalized Hubbard Hamiltonian, many-electron wavefunctions of negatively charged (NV⁻) and neutral nitrogen-vacancy (NV⁰) centers in diamond were calculated. We report the effect of symmetric relaxation of surrounding atoms on the spin density, calculated from the many electron wavefunctions in the ground and excited states. We evaluated the error, that, arises in estimation of spin density when lattice relaxation effect is neglected in Electron Paramagnetic Resonance experiment and showed that the ground state spin density distribution is accessible in outward relaxations. The computed oscillator strengths give a higher efficiency for the 1.945 eV photoluminescence (PL) line of NV⁻ with respect to 2.156 eV PL line of NV⁰ which agrees well with experiment. This result is explained based on the largest the ground state spin among available values for the NV⁻ with respect to NV⁰. The transition probability between degenerate ground and excited states slightly depends on the S_z value. Finally, we report on the electronic configurations which contribute to the ground and excited states and discuss the population variation of electronic configurations with relaxation.