Psi4 – Open-Source Quantum Chemistry

Topic	Replies	Views	Activity
Making Topics that Get Answered Most questions that are answered on the Psi4 Forums are answered by a small group of developers and powerusers. Their time and energy is divided between their own research, further Psi development, and helping users. Acc…	2	4082	August 12, 2019
Welcome to the PSI4 Forum!	1	23428	July 16, 2015
Intruder states in FCI	1	26	June 27, 2025
How to obtain atomic charge distribution for a molecule?	1	29	June 27, 2025
Psi4 Conda Environment MPI Init Error	0	15	June 26, 2025
Matmul error when running geometry optimization	1	22	June 25, 2025
IRC optimization fails with "Math Domain Error" Geometry Optimization	3	165	June 18, 2025
All vibrational calculation by DFT falied due to UnicodeDecodeError	0	15	June 11, 2025
NMR calculation	2	56	June 11, 2025
PSI4 Plugin Interface Developer News & Discussion	0	24	June 10, 2025
New to psi4! I can't get psi4 to work with py 3.12 only 3.7	0	30	June 9, 2025
Psi4 1.6 installer is down	0	17	June 9, 2025
PSA: Psi4 Installers Down	1	77	June 9, 2025
SAPT with external point charges SAPT	0	23	June 8, 2025
Slow CBS frequency calculation	0	13	June 6, 2025
Convert Geometry object to Angstrom	1	27	June 6, 2025
No exception thrown at unconverged geometry opt (geomeTRIC) Geometry Optimization	2	27	May 20, 2025
DFT First order hyperpolarizability (beta) feature-request	0	17	May 16, 2025
Failing convergence of Flexible Molecule - Back transformation failed Geometry Optimization	0	31	May 16, 2025
FREEZE_ALL_DIHEDRALS not valid	1	18	May 15, 2025
Extract force constants from python api?	2	43	May 12, 2025
Does Freeze Core also impact full La-group shells? Geometry Optimization	2	39	May 11, 2025
How do you install `gdma`?	2	32	May 7, 2025
Installation + enable gdma	4	642	May 7, 2025
Does Psi4 work with python 3.13?	3	50	April 29, 2025
Software source not found build	3	42	April 29, 2025
Why is Psi talking about "cc" when I asked for "cc-pVXZ"?	1	40	April 23, 2025
NBO analysis in PSI4 Psi4Education	3	1918	April 23, 2025
Old versions of python	4	36	April 16, 2025
Psi4 "killed" during execution if too many basis/cartesian functions Geometry Optimization	0	24	April 15, 2025

Making Topics that Get Answered

Most questions that are answered on the Psi4 Forums are answered by a small group of developers and powerusers. Their time and energy is divided between their own research, further Psi development, and helping users. Acc…