Spin state of vacancies: From magnetic Jahn-Teller distortions to multiplets

Abstract
The spin configuration of isoelectronic vacancies surrounded by first-row atoms is studied within density-functional theory (DFT) using the local spin density approximation. Allowing for a symmetry break in the electronic system, a mixed-spin state is found to be lowest in energy. It is accompanied by a magnetization density with reduced symmetry indicating a magnetic Jahn-Teller effect. The DFT results are discussed in terms of many-body wave functions of a quantum-chemical treatment. Examples considered are neutral vacancies in diamond and cubic SiC.