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 1301 November 22, 2024
SOC for unrestricted TDDFT
Questions
3 184 March 6, 2026
Gradient and Hessian using CCSD and EOM-CCSD
Questions
3 25 March 5, 2026
Resolution of identity for CDFT?
Questions
6 75 March 3, 2026
ROHF energy discrepancy between Q-Chem and CFOUR
Questions
4 98 February 28, 2026
Optimal settings for large DFT calculations
Questions
3 462 February 28, 2026
Using FRAGMO with ptSS-PCM and CDFT for Vertical Electron Transfer Calculation
Questions
3 64 February 26, 2026
Geometry Optimization with SS_PCM
Questions
1 69 February 25, 2026
Thresh/s2thresh 14?
Questions
8 92 February 24, 2026
Normal Modes Question
Questions
3 220 February 23, 2026
Symmetry in CCSD(T) frequency calculation
Questions
4 98 February 23, 2026
Symmetry of EOM-EA-CCSD. Significance?
Questions
1 108 February 21, 2026
Units of vibrational eigenvectors
Questions
2 107 February 20, 2026
EOM-EA-CCSD on a Excited state
Questions
1 84 February 20, 2026
ROKS emission energy with nonequilibrium solvent
Questions
0 70 February 20, 2026
Dyson orbital using EOMCCSDT-IP
Questions
1 95 February 20, 2026
Frequency calculation speedup
Questions
1 193 February 19, 2026
What is the correct input for the GEOM_OPT_MODE
Questions
2 106 February 19, 2026
Large number of imaginary frequencies with ROKS and delta SCF
Questions
1 84 February 19, 2026
Ehrenfest Molecular Dynamics
Questions
2 83 February 19, 2026
S1 Geom optimization based on TDDFT and delta SCF approach
Questions
11 176 February 18, 2026
Q-Chem license on new MacOS
How To
0 96 February 17, 2026
Stuck CCSD frequency calculation
Questions
2 112 February 16, 2026
Issue with designing functionals
Questions
4 85 February 15, 2026
COSMO input file
Questions
2 100 February 13, 2026
VQCCD single point calculation issue
Questions
0 92 February 13, 2026
RIXS with TDDFT
Questions
0 89 February 12, 2026
Wrong multiplicity for large multiplicity element when using projection based embedding
Questions
3 99 February 12, 2026
Ground state out of equilibrium calculation
Questions
3 164 February 11, 2026
Is it possible to use the NTO-rotated orbitals (for a specific TDDFT state) as the MO set in a subsequent Q-Chem job?
Questions
8 315 February 9, 2026