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 1713 November 22, 2024
Frequency calculation stalls during CPSCF/CPCM-SWIG Hessian step
Questions
3 37 August 31, 2026
Spherical or Cartesian
Questions
4 65 August 26, 2026
r2scan very slow (not scf but doing extra calculations)
How To
1 73 August 20, 2026
Structure Beakdown duing QM/MM calculation
Questions
1 79 August 17, 2026
Q-Chem Webinar 89: M-Chem
Webinars
0 96 August 13, 2026
NAC rem variable error
Questions
1 144 August 5, 2026
ALMO_EDA job failure
Questions
3 637 August 10, 2026
BSSE error input file
Questions
5 697 August 10, 2026
Electron Coupling Calculation with CDFT and CDFT-CI approach
Questions
0 133 August 5, 2026
Webinar 88: What's new in Q-Chem 7
Announcements
0 164 July 28, 2026
CDFT-CI convergence issue
Questions
1 184 July 26, 2026
BOMD of two cationic fragments (coulomb explosion)
Questions
1 208 July 24, 2026
Help with incremental FCI (iFCI) example
Questions
1 918 March 12, 2023
Some doubt regarding CAP onset
Questions
3 231 July 6, 2026
Calculation of transition density matrices between CVS-ADC(2)-x excited states
Questions
0 203 June 30, 2026
Unexpected Energy Ordering in TDDFT Nonequilibrium PCM
Questions
1 227 June 24, 2026
Amber force field generation
Questions
3 305 June 23, 2026
What sort of SCF calculations are supported with external fields?
Questions
5 319 June 16, 2026
CDFT-CI Coupling convergence issue
Questions
5 322 June 15, 2026
ALMO-EDA/COVP SCF Convergence Failure for Open-Shell Anion Radical System
Questions
6 422 June 13, 2026
Lowering amplitude threshold when doing eom CCSD job
Questions
0 231 June 11, 2026
Error in RI-EA-CC2 calculation
Questions
4 495 June 7, 2026
FCIDUMP support
Questions
1 262 June 5, 2026
Upgrade to DFT-D4 in QChem 6.4
Questions
1 294 June 4, 2026
Electronic structures of TDDFT-1D states
Questions
0 277 June 2, 2026
Challenges in CDFT Geometry Optimization Using aug-cc-pVDZ
Questions
1 297 May 29, 2026
Simulating Vibronic and Resonance Raman Spectroscopy Using the VIBRONIC module of Q-Chem
How To
18 4741 May 25, 2026
QM/EFP Setup in Q-Chem with Ghost Atoms Only (Excess Electron in Cavity)
Questions
1 1818 May 22, 2026
Restarting finite difference frequency jobs
Questions
4 1832 May 18, 2026