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	4055	August 12, 2019
Welcome to the PSI4 Forum!	1	23424	July 16, 2015
IRC optimization fails with "Math Domain Error" Geometry Optimization	3	162	June 18, 2025
All vibrational calculation by DFT falied due to UnicodeDecodeError	0	12	June 11, 2025
NMR calculation	2	52	June 11, 2025
PSI4 Plugin Interface Developer News & Discussion	0	21	June 10, 2025
New to psi4! I can't get psi4 to work with py 3.12 only 3.7	0	16	June 9, 2025
Psi4 1.6 installer is down	0	16	June 9, 2025
PSA: Psi4 Installers Down	1	68	June 9, 2025
SAPT with external point charges SAPT	0	15	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	14	May 16, 2025
Failing convergence of Flexible Molecule - Back transformation failed Geometry Optimization	0	22	May 16, 2025
FREEZE_ALL_DIHEDRALS not valid	1	18	May 15, 2025
Extract force constants from python api?	2	38	May 12, 2025
Does Freeze Core also impact full La-group shells? Geometry Optimization	2	39	May 11, 2025
How do you install `gdma`?	1	29	May 7, 2025
Installation + enable gdma	4	639	May 7, 2025
Does Psi4 work with python 3.13?	2	47	April 29, 2025
Software source not found build	3	41	April 29, 2025
Why is Psi talking about "cc" when I asked for "cc-pVXZ"?	1	37	April 23, 2025
NBO analysis in PSI4 Psi4Education	3	1910	April 23, 2025
Old versions of python	4	33	April 16, 2025
Psi4 "killed" during execution if too many basis/cartesian functions Geometry Optimization	0	23	April 15, 2025
Calculating properties from ESP on an isocontour of electronic density	0	16	April 14, 2025
CPHF MO gradients from scfgrad/response.cc do not match finite difference values	3	33	April 10, 2025
C_right_ and C_left_ at jk calculation	4	34	June 3, 2025
FSAPT requires a lot more memory than estimate SAPT	0	42	April 2, 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…