Abstract: Dark current initiated by field emission and multipacting caused by secondary emission have been observed in various radio frequency or microwave components. These phenomena are believed to be major limitations on the stable operation of the particle accelerators, communication satellites and microwave payloads of spacecrafts. This work extends OPAL, a parallel framework for charged particle optics in accelerator structures and beam lines, with the necessary physics models to simulate dark current and multipacting phenomena. Careful benchmark has been performed by code to code comparison with TxPhysics library. After benchmarking, the dark current in highgradient linac structures was evaluated and the post processing capability of OPAL was shown.