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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 1194 November 22, 2024
Visualization/export of SF-TDDFT orbitals
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5 73 January 27, 2026
Error while running frequency calculation
Questions
4 37 January 27, 2026
Frozen atoms move during optimization
Questions
2 30 January 27, 2026
Truncation of non-bonded interactions in QM/MM
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1 31 January 26, 2026
Webinar 85: XCIS-CVS: Core-level Spectroscopy in Q-Chem
Webinars
0 42 January 23, 2026
How to read saved scratch file for hessian
How To
1 37 January 22, 2026
Issue with FRAGMO Optimization: Structural Distortion
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1 54 January 20, 2026
MRSF Transition dipole moment
Questions
2 66 January 20, 2026
Single Na ion calculation using MP2
Questions
2 73 January 16, 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
6 155 January 15, 2026
Using SF-TDDFT single-point energies for TS optimized at DFT level
Questions
1 71 January 13, 2026
Which value to choose when calculating SOC?
Questions
3 78 January 13, 2026
Energy conservation problems during dynamics , bond breaking and forming for collision reaction
Questions
1 76 January 11, 2026
Trouble using EOM-CCSD, with frozen core
Questions
9 250 January 9, 2026
$reorder_mo not affecting beta orbitals as expected
Questions
4 106 January 9, 2026
Conceptual question regarding the applicability of SF-TDDFT method
Questions
1 107 January 9, 2026
Error in EDA 2 calculation
Questions
2 82 January 9, 2026
ALMO_EDA job failure
Questions
1 82 January 9, 2026
Qchem randomly aborting
Questions
3 93 January 7, 2026
How to work with intermolecular distance?
How To
1 91 January 5, 2026
How to define intermolecular distance and charge between two molecule?
How To
3 148 January 3, 2026
Normal Modes Question
Questions
1 86 January 2, 2026
Facing issue with spin-contamination
Questions
1 128 December 29, 2025
Gradient/Force print in cartesian format for each element
Questions
1 98 December 28, 2025
License file for 32 cores in a 128 cores computing node
Questions
1 110 December 24, 2025
Checking the input file for inconsistencies... Error Debug
Questions
3 126 December 23, 2025
Basis set compatibility issue
Questions
3 214 December 23, 2025
IEF-PCM for SMD olvation model
Questions
1 140 December 18, 2025
Possible issue with linear dependencies in the basis when calculating dynamic polarizabilities
Questions
5 193 December 18, 2025