As the boron doping in diamond has been well established, and a negatively charged boron-vacancy (BV) center has an active electron paramagnetic resonance, the BV center is an attractive candidate for spin information devices. Using the first-principles calculation, we report the electronic structure of the BV center in diamond for its various charge states. A geometrically optimized BV center in the diamond supercell exhibited C 3v symmetry. The BV +1 charge state did not exhibit any spin splitting defect levels, while the BV 0 and BV %2 charge states showed a small energy separation between spin-polarized states. On the other hand, the negatively charged BV %1 center possesses bound states with a larger separation inside the diamond bandgap. Moreover, it has the spin-triplet ground state and the spin-conserved triplet excited state. These characteristics indicate that the BV %1 center in diamond is a good candidate for qubit operation.

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