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 1875 November 22, 2024
MRSF-TDDFT triplet-state calculation does not converge
Questions
3 61 October 22, 2026
how to interpret Q-chem output file from Spartan26?
Questions
1 43 October 21, 2026
Using Q-chem via Spartan26. Is it OK to post?
Questions
1 52 October 20, 2026
Imaginary modes, CPCM
Questions
7 1715 October 20, 2026
SA-SF-TDDFT crash
Questions
4 295 October 8, 2026
Best charge analysis options
Questions
1 143 October 5, 2026
Discrepancy in excited-state frequency calculations
Questions
6 286 September 30, 2026
ALMO-FODFT Compatibility with Double-Hybrid Functionals in Q-Chem
Questions
1 264 September 28, 2026
Issues with Bonded ALMO-EDA calculations
Questions
0 172 September 24, 2026
Q-Chem Webinar 90: Modeling materials with Q-Chem 7: overview of QCPBC and what's coming next
Webinars
0 238 September 22, 2026
Does BrianQC support CDFT-CI / legacy SCF engine in Q-Chem7?
Questions
1 225 September 16, 2026
Dyson orbitals between EOM-IP and EOM-DIP states with a CAP active
Questions
0 261 September 2, 2026
Frequency calculation stalls during CPSCF/CPCM-SWIG Hessian step
Questions
3 274 August 31, 2026
Spherical or Cartesian
Questions
4 309 August 26, 2026
r2scan very slow (not scf but doing extra calculations)
How To
1 282 August 20, 2026
Structure Beakdown duing QM/MM calculation
Questions
1 256 August 17, 2026
Q-Chem Webinar 89: M-Chem
Webinars
0 279 August 13, 2026
NAC rem variable error
Questions
1 318 August 5, 2026
ALMO_EDA job failure
Questions
3 848 August 10, 2026
BSSE error input file
Questions
5 878 August 10, 2026
Electron Coupling Calculation with CDFT and CDFT-CI approach
Questions
0 333 August 5, 2026
Webinar 88: What's new in Q-Chem 7
Announcements
0 335 July 28, 2026
CDFT-CI convergence issue
Questions
1 368 July 26, 2026
BOMD of two cationic fragments (coulomb explosion)
Questions
1 394 July 24, 2026
Help with incremental FCI (iFCI) example
Questions
1 1049 March 12, 2023
Some doubt regarding CAP onset
Questions
3 417 July 6, 2026
Calculation of transition density matrices between CVS-ADC(2)-x excited states
Questions
0 351 June 30, 2026
Unexpected Energy Ordering in TDDFT Nonequilibrium PCM
Questions
1 387 June 24, 2026
Amber force field generation
Questions
3 494 June 23, 2026