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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…

3 857 November 22, 2024
How does IQmol calculate the center of mass of a molecule?
Questions
0 1 October 31, 2025
TSVDW and MBD crashes
Questions
1 29 October 30, 2025
Unexpected behaviour: core orbitals are not frozen during MP2/MP3 step in ADC calculations
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4 97 October 27, 2025
SCF convergence issue with diffuse functions on basis set
Questions
27 281 October 22, 2025
Problem oxygen potential energy scan using CCSD(T) and EA state PES using EA-EOM-CCSD
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8 247 October 22, 2025
Crash upon frequency calculations with range separated bybrid
Questions
1 85 October 21, 2025
Cryptic import_xcfunc warning
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10 158 October 20, 2025
What sort of RI techniques are safe to use with different types of SCF?
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3 118 October 16, 2025
RI worsens SCF timings
Questions
4 125 October 16, 2025
EOMCCSDT calculations
How To
2 190 September 29, 2025
Question on calculating IPs (cationic states) for L-shell orbitals with IP-EOM-CCSD or ADC(3)
Questions
14 182 October 9, 2025
Is CVS approximation available for IP-ADC(3)?
Questions
0 105 October 9, 2025
Single Point immediately fails with DM alg and AUTOSAD guess
Questions
4 133 October 8, 2025
Keywords for printing <S^2> values using unrestricted TDDFT (RPA=2)
Questions
2 262 October 7, 2025
Clarification on RASSCF Calculation of Multiple Spin States in Q-Chem
Questions
2 144 October 6, 2025
Fchk file size increased with Q-Chem 6.1?
Questions
4 603 October 3, 2025
Irreducible representation of electrons
How To
1 114 October 3, 2025
Saving SCF Metadynamics Solutions
Questions
0 118 October 2, 2025
Are there specific command to print the gradient matrix?
Questions
6 205 October 2, 2025
Unkown error encountered in a ET coupling calculation using CC2
Questions
1 147 October 1, 2025
EOM-CCSD job FOR SINGLET TRIPLET STATE in Q-Chem stuck during SCF convergence
Questions
1 181 October 1, 2025
“ADC(3) singlet and triplet excited states with PCM – input and disk quota issues”
Questions
1 128 October 1, 2025
How to find the radial shells?
Questions
1 116 September 30, 2025
Multiple simultaneous Field_Types?
Questions
3 125 September 30, 2025
Different (larger) SCF energy compared to other software (Orca, C4) when using an augmented (aug-cc-pVDZ) basis set
Questions
7 174 September 29, 2025
Printing T and R amplitudes in (EOM-)CCSD calculation
Questions
2 222 September 28, 2025
QCHEM licence under wsl2 ubuntu system
Questions
1 119 September 27, 2025
Too many atoms of one type in orbmat
Questions
9 146 September 25, 2025
Fuller context of error messages
How To
1 140 September 24, 2025