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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 1148 November 22, 2024
Energy conservation problems during dynamics , bond breaking and forming for collision reaction
Questions
0 13 January 10, 2026
Trouble using EOM-CCSD, with frozen core
Questions
9 193 January 9, 2026
$reorder_mo not affecting beta orbitals as expected
Questions
4 41 January 9, 2026
Conceptual question regarding the applicability of SF-TDDFT method
Questions
1 52 January 9, 2026
Error in EDA 2 calculation
Questions
2 32 January 9, 2026
ALMO_EDA job failure
Questions
1 27 January 9, 2026
Qchem randomly aborting
Questions
3 42 January 7, 2026
How to work with intermolecular distance?
How To
1 42 January 5, 2026
Is it possible to use the NTO-rotated orbitals (for a specific TDDFT state) as the MO set in a subsequent Q-Chem job?
Questions
4 87 January 4, 2026
How to define intermolecular distance and charge between two molecule?
How To
3 91 January 3, 2026
Normal Modes Question
Questions
1 51 January 2, 2026
Facing issue with spin-contamination
Questions
1 81 December 29, 2025
Gradient/Force print in cartesian format for each element
Questions
1 61 December 28, 2025
License file for 32 cores in a 128 cores computing node
Questions
1 64 December 24, 2025
Checking the input file for inconsistencies... Error Debug
Questions
3 86 December 23, 2025
Basis set compatibility issue
Questions
3 138 December 23, 2025
IEF-PCM for SMD olvation model
Questions
1 89 December 18, 2025
Possible issue with linear dependencies in the basis when calculating dynamic polarizabilities
Questions
5 133 December 18, 2025
downloading and installing qcIntel version 6402
Questions
1 100 December 17, 2025
Discrepancies between RIMP2 polarizabilities with FDIF = 0 and FDIF = 1
Questions
1 95 December 12, 2025
Excitation energy transfer between two carotinoids
Questions
3 124 December 12, 2025
Machine learned PES
Questions
1 153 December 1, 2025
Partial frozen scan
Questions
3 154 November 29, 2025
Dipole Moments with MBD dispersion
Questions
1 119 November 28, 2025
Correlation consistent basis sets and effective core potentials should be included?
Questions
1 191 November 28, 2025
vdW-TS (MBDVDW) vibrational frequencies
Questions
15 249 November 27, 2025
neo-scf calculations
Questions
1 108 November 25, 2025
aug-cc-pV(n+d)Z basis sets
Questions
1 119 November 25, 2025
Cannot get rid of Imaginary Frequency
Questions
3 189 November 25, 2025