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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…

3 986 November 22, 2024
Problem oxygen potential energy scan using CCSD(T) and EA state PES using EA-EOM-CCSD
Questions
11 393 November 11, 2025
“double free or corruption (out)” error in TDDFT + EFP job with large number of fragments
Questions
1 56 November 9, 2025
Cannot escape an imaginary frequency
Questions
1 82 November 7, 2025
Second Derivative for DC-DFT
How To
8 87 November 6, 2025
Limited support for analytic Hessians in Q-Chem
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10 796 November 6, 2025
How does IQmol calculate the center of mass of a molecule?
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1 90 November 1, 2025
TSVDW and MBD crashes
Questions
1 96 October 30, 2025
Unexpected behaviour: core orbitals are not frozen during MP2/MP3 step in ADC calculations
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4 210 October 27, 2025
SCF convergence issue with diffuse functions on basis set
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27 395 October 22, 2025
Crash upon frequency calculations with range separated bybrid
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1 181 October 21, 2025
Cryptic import_xcfunc warning
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10 260 October 20, 2025
What sort of RI techniques are safe to use with different types of SCF?
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3 211 October 16, 2025
RI worsens SCF timings
Questions
4 219 October 16, 2025
EOMCCSDT calculations
How To
2 282 September 29, 2025
Question on calculating IPs (cationic states) for L-shell orbitals with IP-EOM-CCSD or ADC(3)
Questions
14 273 October 9, 2025
Is CVS approximation available for IP-ADC(3)?
Questions
0 191 October 9, 2025
Single Point immediately fails with DM alg and AUTOSAD guess
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4 223 October 8, 2025
Keywords for printing <S^2> values using unrestricted TDDFT (RPA=2)
Questions
2 353 October 7, 2025
Clarification on RASSCF Calculation of Multiple Spin States in Q-Chem
Questions
2 239 October 6, 2025
Fchk file size increased with Q-Chem 6.1?
Questions
4 695 October 3, 2025
Irreducible representation of electrons
How To
1 207 October 3, 2025
Saving SCF Metadynamics Solutions
Questions
0 207 October 2, 2025
Are there specific command to print the gradient matrix?
Questions
6 296 October 2, 2025
Unkown error encountered in a ET coupling calculation using CC2
Questions
1 247 October 1, 2025
EOM-CCSD job FOR SINGLET TRIPLET STATE in Q-Chem stuck during SCF convergence
Questions
1 351 October 1, 2025
“ADC(3) singlet and triplet excited states with PCM – input and disk quota issues”
Questions
1 252 October 1, 2025
How to find the radial shells?
Questions
1 211 September 30, 2025
Multiple simultaneous Field_Types?
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3 212 September 30, 2025
Different (larger) SCF energy compared to other software (Orca, C4) when using an augmented (aug-cc-pVDZ) basis set
Questions
7 294 September 29, 2025