Barca, Giuseppe Maria JuniorBertoni, ColleenCarrington, LauraDatta, Dipayande Silva, NuwanDeustua, J. EmilianoFedorov, Dmitri G.Gour, Jeffrey R.Gunina, Anastasia O.Guidez, EmilieHarville, TaylorIrle, StephanRendell, Alistair2023-12-042023-12-040021-9606http://hdl.handle.net/1885/307653A discussion of many of the recently implemented features of GAMESS (General Atomic and Molecular Electronic Structure System) and LibCChem (the C++ CPU/GPU library associated with GAMESS) is presented. These features include fragmentation methods such as the fragment molecular orbital, effective fragment potential and effective fragment molecular orbital methods, hybrid MPI/OpenMP approaches to Hartree-Fock, and resolution of the identity second order perturbation theory. Many new coupled cluster theory methods have been implemented in GAMESS, as have multiple levels of density functional/tight binding theory. The role of accelerators, especially graphical processing units, is discussed in the context of the new features of LibCChem, as it is the associated problem of power consumption as the power of computers increases dramatically. The process by which a complex program suite such as GAMESS is maintained and developed is considered. Future developments are briefly summarized.The development of GAMESS was supported by several agencies, including the Air Force Office of Scientific Research, the Department of Defense, the Department of Energy, the National Science Foundation, and the National Institutes of Health and was also supported by Intel, Microsoft, and NVIDIA. The members of the GAMESS development group are very grateful for this support.application/pdfen-AU© 2020 AIP2020-04-1610.1063/5.00051882022-09-04