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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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Using FRAGMO with ptSS-PCM and CDFT for Vertical Electron Transfer Calculation
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1 69 February 19, 2026
What is the correct input for the GEOM_OPT_MODE
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Large number of imaginary frequencies with ROKS and delta SCF
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1 63 February 19, 2026
Ehrenfest Molecular Dynamics
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S1 Geom optimization based on TDDFT and delta SCF approach
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11 149 February 18, 2026
Q-Chem license on new MacOS
How To
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Stuck CCSD frequency calculation
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Wrong multiplicity for large multiplicity element when using projection based embedding
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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?
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8 278 February 9, 2026
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Questions
1 87 February 6, 2026
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Questions
2 154 January 30, 2026