Paste Gaussian text or enter values manually below. Compare thermal terms, frequencies, and stability flags. Get organized exports, example data, formulas, and practical guidance.
| Label | Electronic Energy (Hartree) | Gibbs Correction (Hartree) | Total Gibbs (Hartree) | Imaginary Count | Lowest Frequency (cm⁻¹) | Interpretation |
|---|---|---|---|---|---|---|
| Min-1 | -228.123456 | 0.145678 | -227.977778 | 0 | 28.4410 | Local minimum |
| TS-1 | -228.100210 | 0.142100 | -227.958110 | 1 | -312.5500 | Transition-state candidate |
| HS-1 | -228.090111 | 0.140555 | -227.949556 | 2 | -145.3200 | Higher-order saddle warning |
Total Gibbs free energy: G = Eelectronic + Gcorrection
Relative Gibbs free energy: ΔG = Gpoint − Greference
Imaginary frequency count: count all frequencies smaller than zero.
Point classification: zero imaginary frequencies suggest a minimum, one suggests a transition-state candidate, and more than one suggests a higher-order saddle or non-stationary structure.
Gradient check: if the gradient norm exceeds the chosen threshold, the geometry may still be non-stationary even when the frequency pattern looks acceptable.
Gaussian output often contains everything needed to evaluate a structure after optimization and frequency analysis. The most useful values are the electronic energy, the thermal correction to Gibbs free energy, and the final sum of electronic and thermal free energies. This calculator brings those values together and checks whether the structure behaves like a minimum, a transition state, or a problematic point.
A well-behaved minimum should have no imaginary frequencies. A transition state should usually have exactly one imaginary frequency that matches the expected reaction coordinate. If you find more than one imaginary frequency, the geometry is usually not ready for interpretation. It may represent a higher-order saddle or an incomplete optimization. A large remaining gradient can also signal that the structure is not truly stationary.
Gaussian commonly reports the thermal correction to Gibbs free energy and also the summed free energy. If the summed free energy is present, the calculator uses it directly. If only the electronic energy and Gibbs correction are available, the calculator adds them to reconstruct the total Gibbs value. You can also compare one structure against a reference structure through a relative ΔG calculation.
The classification field tells you whether the point looks like a minimum, a transition-state candidate, or a likely non-stationary structure. The lowest frequency helps you spot suspicious soft modes. The warning block explains whether your expected point type conflicts with the observed imaginary frequency count. The summary table and charts help you report results clearly in computational chemistry workflows, validation notes, conformer screening, or reaction path studies.
It estimates Gibbs free energy, counts imaginary frequencies, checks gradient thresholds, and labels the structure as a minimum, transition-state candidate, or likely non-stationary point.
Yes. Paste lines containing SCF energy, thermal Gibbs correction, free energy sum, and frequencies. The parser will try to extract those values automatically.
The calculator rebuilds total Gibbs free energy from the electronic energy and thermal Gibbs correction when both values are available.
One imaginary frequency often indicates a first-order saddle. That is usually correct for a transition-state candidate, provided the mode matches the intended reaction path.
More than one imaginary frequency usually means the geometry is not a proper minimum or simple transition state. Re-optimization is commonly needed.
Yes. Enter a reference Gibbs free energy and the tool will calculate relative Gibbs free energy for the current structure.
Manual energy inputs can be entered in Hartree, kJ/mol, kcal/mol, or eV. Internally, values are converted for consistent calculations.
No. It is a reporting and screening tool. Final interpretation still depends on mode inspection, convergence quality, and the chemical context.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.