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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 1174 November 22, 2024
Visualization/export of SF-TDDFT orbitals
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1 14 January 21, 2026
Issue with FRAGMO Optimization: Structural Distortion
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1 27 January 20, 2026
MRSF Transition dipole moment
Questions
2 41 January 20, 2026
Single Na ion calculation using MP2
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2 59 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
6 137 January 15, 2026
Using SF-TDDFT single-point energies for TS optimized at DFT level
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1 58 January 13, 2026
Which value to choose when calculating SOC?
Questions
3 60 January 13, 2026
Energy conservation problems during dynamics , bond breaking and forming for collision reaction
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1 62 January 11, 2026
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9 230 January 9, 2026
$reorder_mo not affecting beta orbitals as expected
Questions
4 89 January 9, 2026
Conceptual question regarding the applicability of SF-TDDFT method
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1 90 January 9, 2026
Error in EDA 2 calculation
Questions
2 69 January 9, 2026
ALMO_EDA job failure
Questions
1 66 January 9, 2026
Qchem randomly aborting
Questions
3 72 January 7, 2026
How to work with intermolecular distance?
How To
1 72 January 5, 2026
How to define intermolecular distance and charge between two molecule?
How To
3 125 January 3, 2026
Normal Modes Question
Questions
1 72 January 2, 2026
Facing issue with spin-contamination
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1 112 December 29, 2025
Gradient/Force print in cartesian format for each element
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1 82 December 28, 2025
License file for 32 cores in a 128 cores computing node
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1 92 December 24, 2025
Checking the input file for inconsistencies... Error Debug
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3 108 December 23, 2025
Basis set compatibility issue
Questions
3 184 December 23, 2025
IEF-PCM for SMD olvation model
Questions
1 119 December 18, 2025
Possible issue with linear dependencies in the basis when calculating dynamic polarizabilities
Questions
5 165 December 18, 2025
downloading and installing qcIntel version 6402
Questions
1 129 December 17, 2025
Discrepancies between RIMP2 polarizabilities with FDIF = 0 and FDIF = 1
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1 122 December 12, 2025
Excitation energy transfer between two carotinoids
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3 150 December 12, 2025
Machine learned PES
Questions
1 176 December 1, 2025
Partial frozen scan
Questions
3 178 November 29, 2025