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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 1242 November 22, 2024
Stuck CCSD frequency calculation
Questions
2 44 February 16, 2026
Issue with designing functionals
Questions
4 34 February 15, 2026
S1 Geom optimization based on TDDFT and delSCF approach
Questions
3 49 February 15, 2026
What is the correct input for the GEOM_OPT_MODE
Questions
1 35 February 13, 2026
COSMO input file
Questions
2 39 February 13, 2026
VQCCD single point calculation issue
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0 35 February 13, 2026
RIXS with TDDFT
Questions
0 40 February 12, 2026
Wrong multiplicity for large multiplicity element when using projection based embedding
Questions
3 51 February 12, 2026
Ground state out of equilibrium calculation
Questions
3 102 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
8 232 February 9, 2026
CASSCF with Nonadiabatic Coupling
Questions
1 61 February 6, 2026
Complex Scaling on Q-Chem
Questions
3 78 February 6, 2026
SOC for Diabatic-State-Based Methods
Questions
3 87 February 2, 2026
SOC for unrestricted TDDFT
Questions
2 110 January 30, 2026
Visualization/export of SF-TDDFT orbitals
Questions
5 160 January 27, 2026
Error while running frequency calculation
Questions
4 103 January 27, 2026
Frozen atoms move during optimization
Questions
2 109 January 27, 2026
Truncation of non-bonded interactions in QM/MM
Questions
1 79 January 26, 2026
Webinar 85: XCIS-CVS: Core-level Spectroscopy in Q-Chem
Webinars
0 90 January 23, 2026
How to read saved scratch file for hessian
How To
1 98 January 22, 2026
Issue with FRAGMO Optimization: Structural Distortion
Questions
1 93 January 20, 2026
MRSF Transition dipole moment
Questions
2 103 January 20, 2026
Single Na ion calculation using MP2
Questions
2 117 January 16, 2026
Using SF-TDDFT single-point energies for TS optimized at DFT level
Questions
1 114 January 13, 2026
Which value to choose when calculating SOC?
Questions
3 124 January 13, 2026
Energy conservation problems during dynamics , bond breaking and forming for collision reaction
Questions
1 107 January 11, 2026
Trouble using EOM-CCSD, with frozen core
Questions
9 295 January 9, 2026
$reorder_mo not affecting beta orbitals as expected
Questions
4 153 January 9, 2026
Conceptual question regarding the applicability of SF-TDDFT method
Questions
1 145 January 9, 2026