Singlet–triplet spin–orbit coupling and crossing probability for the single-dimer cluster model of a Si(1 0 0) surface

The minimum energy crossing point of the singlet to triplet crossing for a single Si-dimer cluster has been determined using a variety of computational techniques. The crossing points located by the various computational methods were similar in structure and close to the triplet state in energy. At the crossing point, the spin–orbit coupling (SOC) coefficient was determined to be approximately 25 cm−1. Small geometry differences at the crossing points located by the different computational methods had insignificant influence on this value. Using this SOC, the Landau–Zener spin-crossing probability at room temperature was computed to be approximately 0.5%.