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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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Checking the input file for inconsistencies... Error Debug
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Partial frozen scan
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Correlation consistent basis sets and effective core potentials should be included?
Questions
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vdW-TS (MBDVDW) vibrational frequencies
Questions
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neo-scf calculations
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1 78 November 25, 2025
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Questions
1 85 November 25, 2025
Cannot get rid of Imaginary Frequency
Questions
3 137 November 25, 2025
TDA with RSH giving negative triplet excitation
Questions
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“ADC(3) singlet and triplet excited states with PCM – input and disk quota issues”
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How To
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2 100 November 19, 2025
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Questions
6 135 November 19, 2025
Issue with S₁ State Optimization Under PCM – SCF Convergence Error
Questions
3 126 November 18, 2025
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Questions
7 162 November 17, 2025
Problem oxygen potential energy scan using CCSD(T) and EA state PES using EA-EOM-CCSD
Questions
11 552 November 11, 2025
“double free or corruption (out)” error in TDDFT + EFP job with large number of fragments
Questions
1 140 November 9, 2025
Cannot escape an imaginary frequency
Questions
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Questions
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