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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…

3 922 November 22, 2024
Cannot escape an imaginary frequency
Questions
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How To
8 49 November 6, 2025
Limited support for analytic Hessians in Q-Chem
Questions
10 758 November 6, 2025
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1 55 November 1, 2025
TSVDW and MBD crashes
Questions
1 62 October 30, 2025
Unexpected behaviour: core orbitals are not frozen during MP2/MP3 step in ADC calculations
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4 163 October 27, 2025
SCF convergence issue with diffuse functions on basis set
Questions
27 354 October 22, 2025
Problem oxygen potential energy scan using CCSD(T) and EA state PES using EA-EOM-CCSD
Questions
8 316 October 22, 2025
Crash upon frequency calculations with range separated bybrid
Questions
1 140 October 21, 2025
Cryptic import_xcfunc warning
Questions
10 219 October 20, 2025
What sort of RI techniques are safe to use with different types of SCF?
Questions
3 169 October 16, 2025
RI worsens SCF timings
Questions
4 181 October 16, 2025
EOMCCSDT calculations
How To
2 244 September 29, 2025
Question on calculating IPs (cationic states) for L-shell orbitals with IP-EOM-CCSD or ADC(3)
Questions
14 240 October 9, 2025
Is CVS approximation available for IP-ADC(3)?
Questions
0 154 October 9, 2025
Single Point immediately fails with DM alg and AUTOSAD guess
Questions
4 188 October 8, 2025
Keywords for printing <S^2> values using unrestricted TDDFT (RPA=2)
Questions
2 319 October 7, 2025
Clarification on RASSCF Calculation of Multiple Spin States in Q-Chem
Questions
2 202 October 6, 2025
Fchk file size increased with Q-Chem 6.1?
Questions
4 657 October 3, 2025
Irreducible representation of electrons
How To
1 168 October 3, 2025
Saving SCF Metadynamics Solutions
Questions
0 172 October 2, 2025
Are there specific command to print the gradient matrix?
Questions
6 261 October 2, 2025
Unkown error encountered in a ET coupling calculation using CC2
Questions
1 206 October 1, 2025
EOM-CCSD job FOR SINGLET TRIPLET STATE in Q-Chem stuck during SCF convergence
Questions
1 285 October 1, 2025
“ADC(3) singlet and triplet excited states with PCM – input and disk quota issues”
Questions
1 192 October 1, 2025
How to find the radial shells?
Questions
1 172 September 30, 2025
Multiple simultaneous Field_Types?
Questions
3 176 September 30, 2025
Different (larger) SCF energy compared to other software (Orca, C4) when using an augmented (aug-cc-pVDZ) basis set
Questions
7 241 September 29, 2025
Printing T and R amplitudes in (EOM-)CCSD calculation
Questions
2 324 September 28, 2025