  In quantum technologies, point defects in semiconductors are becoming more
significant. Understanding the frequency, intensity, and polarization of the
zero phonon line is important. The last two properties are the subject of this
paper. I present a method for calculating these properties and show the
importance of using wave functions from both the ground and excited state. The
validity of this method is demonstrated on the divacancy in 4H-SiC. Here, the
calculated polarization and lifetimes are in excellent agreement with
experimental measurements. In general, this method can help to identify point
defects and estimate suitable applications.
