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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 1798 November 22, 2024
Discrepancy in excited-state frequency calculations
Questions
6 76 September 30, 2026
ALMO-FODFT Compatibility with Double-Hybrid Functionals in Q-Chem
Questions
1 152 September 28, 2026
SA-SF-TDDFT crash
Questions
1 85 September 26, 2026
Issues with Bonded ALMO-EDA calculations
Questions
0 56 September 24, 2026
Q-Chem Webinar 90: Modeling materials with Q-Chem 7: overview of QCPBC and what's coming next
Webinars
0 114 September 22, 2026
Does BrianQC support CDFT-CI / legacy SCF engine in Q-Chem7?
Questions
1 117 September 16, 2026
Dyson orbitals between EOM-IP and EOM-DIP states with a CAP active
Questions
0 141 September 2, 2026
Frequency calculation stalls during CPSCF/CPCM-SWIG Hessian step
Questions
3 175 August 31, 2026
Spherical or Cartesian
Questions
4 202 August 26, 2026
r2scan very slow (not scf but doing extra calculations)
How To
1 171 August 20, 2026
Structure Beakdown duing QM/MM calculation
Questions
1 172 August 17, 2026
Q-Chem Webinar 89: M-Chem
Webinars
0 188 August 13, 2026
NAC rem variable error
Questions
1 235 August 5, 2026
ALMO_EDA job failure
Questions
3 748 August 10, 2026
BSSE error input file
Questions
5 805 August 10, 2026
Electron Coupling Calculation with CDFT and CDFT-CI approach
Questions
0 242 August 5, 2026
Webinar 88: What's new in Q-Chem 7
Announcements
0 268 July 28, 2026
CDFT-CI convergence issue
Questions
1 277 July 26, 2026
BOMD of two cationic fragments (coulomb explosion)
Questions
1 306 July 24, 2026
Help with incremental FCI (iFCI) example
Questions
1 976 March 12, 2023
Some doubt regarding CAP onset
Questions
3 337 July 6, 2026
Calculation of transition density matrices between CVS-ADC(2)-x excited states
Questions
0 276 June 30, 2026
Unexpected Energy Ordering in TDDFT Nonequilibrium PCM
Questions
1 308 June 24, 2026
Amber force field generation
Questions
3 408 June 23, 2026
What sort of SCF calculations are supported with external fields?
Questions
5 421 June 16, 2026
CDFT-CI Coupling convergence issue
Questions
5 432 June 15, 2026
ALMO-EDA/COVP SCF Convergence Failure for Open-Shell Anion Radical System
Questions
6 527 June 13, 2026
Lowering amplitude threshold when doing eom CCSD job
Questions
0 312 June 11, 2026
Error in RI-EA-CC2 calculation
Questions
4 579 June 7, 2026