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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 1154 November 22, 2024
Using SF-TDDFT single-point energies for TS optimized at DFT level
Questions
1 10 January 13, 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
5 97 January 13, 2026
Which value to choose when calculating SOC?
Questions
3 15 January 13, 2026
Energy conservation problems during dynamics , bond breaking and forming for collision reaction
Questions
1 36 January 11, 2026
Trouble using EOM-CCSD, with frozen core
Questions
9 203 January 9, 2026
$reorder_mo not affecting beta orbitals as expected
Questions
4 59 January 9, 2026
Conceptual question regarding the applicability of SF-TDDFT method
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1 64 January 9, 2026
Error in EDA 2 calculation
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2 45 January 9, 2026
ALMO_EDA job failure
Questions
1 38 January 9, 2026
Qchem randomly aborting
Questions
3 51 January 7, 2026
How to work with intermolecular distance?
How To
1 50 January 5, 2026
How to define intermolecular distance and charge between two molecule?
How To
3 96 January 3, 2026
Normal Modes Question
Questions
1 54 January 2, 2026
Facing issue with spin-contamination
Questions
1 86 December 29, 2025
Gradient/Force print in cartesian format for each element
Questions
1 65 December 28, 2025
License file for 32 cores in a 128 cores computing node
Questions
1 69 December 24, 2025
Checking the input file for inconsistencies... Error Debug
Questions
3 92 December 23, 2025
Basis set compatibility issue
Questions
3 147 December 23, 2025
IEF-PCM for SMD olvation model
Questions
1 96 December 18, 2025
Possible issue with linear dependencies in the basis when calculating dynamic polarizabilities
Questions
5 141 December 18, 2025
downloading and installing qcIntel version 6402
Questions
1 106 December 17, 2025
Discrepancies between RIMP2 polarizabilities with FDIF = 0 and FDIF = 1
Questions
1 103 December 12, 2025
Excitation energy transfer between two carotinoids
Questions
3 130 December 12, 2025
Machine learned PES
Questions
1 158 December 1, 2025
Partial frozen scan
Questions
3 161 November 29, 2025
Dipole Moments with MBD dispersion
Questions
1 122 November 28, 2025
Correlation consistent basis sets and effective core potentials should be included?
Questions
1 196 November 28, 2025
vdW-TS (MBDVDW) vibrational frequencies
Questions
15 262 November 27, 2025
neo-scf calculations
Questions
1 113 November 25, 2025