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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…

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SOC for unrestricted TDDFT
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1 86 February 20, 2026
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0 72 February 20, 2026
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1 96 February 20, 2026
Frequency calculation speedup
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1 194 February 19, 2026
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Large number of imaginary frequencies with ROKS and delta SCF
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1 86 February 19, 2026
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11 178 February 18, 2026
Q-Chem license on new MacOS
How To
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Stuck CCSD frequency calculation
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COSMO input file
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0 90 February 12, 2026
Wrong multiplicity for large multiplicity element when using projection based embedding
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3 100 February 12, 2026
Ground state out of equilibrium calculation
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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
8 318 February 9, 2026