Topic Replies Views Activity
Report SCF (HF/DFT) Convergence Issues
Questions

Dear Q-Chem Community, If you have any SCF (HF/DFT) jobs that are time-consuming or are facing convergence difficulties with Q-Chem, please send them to support@q-chem.com with the subject line “SCF Convergence Issue” t…

3 1509 November 22, 2024
CDFT-CI Coupling convergence issue
Questions
4 59 June 14, 2026
ALMO-EDA/COVP SCF Convergence Failure for Open-Shell Anion Radical System
Questions
6 114 June 13, 2026
Lowering amplitude threshold when doing eom CCSD job
Questions
0 31 June 11, 2026
Error in RI-EA-CC2 calculation
Questions
4 284 June 7, 2026
FCIDUMP support
Questions
1 65 June 5, 2026
Upgrade to DFT-D4 in QChem 6.4
Questions
1 74 June 4, 2026
Electronic structures of TDDFT-1D states
Questions
0 80 June 2, 2026
Challenges in CDFT Geometry Optimization Using aug-cc-pVDZ
Questions
1 89 May 29, 2026
Simulating Vibronic and Resonance Raman Spectroscopy Using the VIBRONIC module of Q-Chem
How To
18 4146 May 25, 2026
QM/EFP Setup in Q-Chem with Ghost Atoms Only (Excess Electron in Cavity)
Questions
1 115 May 22, 2026
Restarting finite difference frequency jobs
Questions
4 1638 May 18, 2026
“ADC(3) singlet and triplet excited states with PCM – input and disk quota issues”
Questions
4 573 May 18, 2026
aug-cc-pV5Z with external charges
Questions
3 195 May 13, 2026
CDFT block set up
How To
1 152 May 7, 2026
New basis set - excited states of Argon
Questions
3 212 May 5, 2026
PES scan not respecting mem_total
Questions
6 187 May 4, 2026
How to use SGM method to calculate triplet excited states with ROKS?
Questions
3 212 May 3, 2026
Improving the accuracy of CPHF
Questions
1 164 May 1, 2026
TDDFT SOC results
Questions
3 281 April 28, 2026
Failure in Frequency job
Questions
3 204 April 24, 2026
Webinar 87: Improvements in the OO-DFT user interface
Webinars
0 180 April 23, 2026
Facing convergence issue with CDFT geometry optimization
Questions
1 186 April 22, 2026
Loading basis set from file?
Questions
1 189 April 22, 2026
Non-adiabatic bimolecular reaction dynamics
Questions
5 291 April 18, 2026
Energy inconsistency with PySCF / adcc
Questions
3 282 April 17, 2026
Facing Imaginary frequency in excited state
Questions
1 209 April 17, 2026
Issue with fragment job submission in Q-Chem 5.0.1 EDA calculations
Questions
3 228 April 13, 2026
Crash with NO_REORIENT
Questions
4 255 April 10, 2026
Facing large number of imaginary frequencies in LRC-wPBE functional
Questions
3 239 April 7, 2026