Primary development on PSI is being carried out in the following research groups.
- Center for Computational Quantum Chemistry (CCQC) at the University of Georgia
- C. David Sherrill at Georgia Tech
- T. Daniel Crawford at Virginia Tech
- Edward F. Valeev at Virginia Tech
- Rollin A. King at Bethel University
- Eugene DePrince at Florida State University
- Ugur Bozkaya at Ataturk University