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	4275	August 12, 2019
Welcome to the PSI4 Forum!	1	23582	July 16, 2015
Using DLPNO-CCSD(T) with canonical PCM in PSI4	0	15	May 28, 2026
Psi4 installation in Google Colab not working	0	15	May 20, 2026
CCSD(T) 1 particle density matrix	2	28	May 7, 2026
Error with: "module 'psi4' has no attribute 'fsapt_analysis'"	0	13	May 5, 2026
Freezing Cartesian Errors Geometry Optimization	3	99	April 24, 2026
Positive induction due to pseudopotentials? SAPT	0	15	April 17, 2026
SCF dynamic polarizability	2	61	February 28, 2026
Accessing IntegralFactory from python	0	100	February 18, 2026
Reading wavefunctions from wfx, Molden or fchk? feature-request	0	57	January 30, 2026
Question about memory settings in SAPT(DFT) SAPT	0	65	January 26, 2026
Gau_xc not working build	0	51	December 22, 2025
Eigen Not Compiling When Building From Source on Mac build	1	97	December 9, 2025
Atom Excited States - Transition Metals	0	60	December 7, 2025
Counterpoise correction and projected Hessian	2	128	November 18, 2025
Exporting Natural Orbitals as wfn object to PsiAPI Python interface build	1	95	October 30, 2025
Exporting natural orbitals	0	58	October 27, 2025
Eom-cc2, eom-cc3 for triplet state	0	98	October 23, 2025
Questions on Psi4 performance and scaling on HPC systems build	0	124	September 12, 2025
All vibrational calculation by DFT falied due to UnicodeDecodeError	1	117	August 29, 2025
Error on Windows 10 Installation	0	79	August 22, 2025
Warning message when writing a Molden file + Molden file from MPx calculations	0	59	August 15, 2025
DKH Hamiltonian 4th order SCF convergence issues	0	59	August 3, 2025
Intruder states in FCI	1	95	June 27, 2025
How to obtain atomic charge distribution for a molecule?	1	127	June 27, 2025
Psi4 Conda Environment MPI Init Error	0	84	June 26, 2025
Matmul error when running geometry optimization	2	84	June 25, 2025
IRC optimization fails with "Math Domain Error" Geometry Optimization	3	254	June 18, 2025
NMR calculation	2	180	June 11, 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…