Domain 6 of 10
Solvent Effects, Stated with Their Limits
Continuum solvation for energies, geometries and frequencies, plus pKa and redox potentials from thermodynamic cycles.
12 PartialEngine 1.10.12 live
What You Can Compute
Continuum Models
IEF-PCM and COSMO with continuous surface charges for energies, gradients and frequencies.
Nonpolar and SMD
SMD in water and in organic solvents with your descriptors, Generalized Born and MM/GBSA.
pKa and Redox
Thermodynamic cycles with the proton term and stated uncertainty, absolute or relative.
Electrochemistry
Hydrogen electrode free energy steps, Pourbaix diagrams and the cluster-continuum scheme for ions; the redox cycle reproduces the absolute hydrogen electrode potentials of Marenich et al. 2014 Table 2.
Every Method, with Its Level of Support
Generated from the engine's own capability report (engine 1.10.12), so this list never runs ahead of the code.
Checked reproduces printed values Checked (exact) no printed value exists; checked against exact mathematics or brute force Partial code exists, unchecked parts badged in the app Unverified built, no printed check yet
| Method | Support | Since | Primary Sources |
|---|---|---|---|
| IEF-PCMContinuous surface charge PCM for energies, gradients and frequencies. | Partial | 0.7.30 | Cances, Mennucci, Tomasi 1997; Scalmani, Frisch 2010 |
| COSMOConductor-like screening with segments for COSMO-RS. Equations follow Klamt et al. 1998; Klamt, Schuurmann 1993 is the original formalism. Checked against IEF-PCM and exact conductor results; no printed molecular COSMO energy is reproduced yet. | Partial | 0.9.5 | Klamt et al. 1998; Klamt, Schuurmann 1993 |
| SMD (water)SMD cavity-dispersion-solvent structure term in water. Water only. The parameter tables (Marenich, Cramer, Truhlar 2009 Tables 3 to 5 and Supporting Information Part III) were read twice with identical results but are still flagged unverified by the engine. The term is checked against independent evaluations of the printed formulas, exact sphere and cap areas (within 1.5 %) and finite-difference gradients. No printed energy is reproduced: the paper prints error statistics, not values for single molecules. Organic solvents are listed separately below. | Partial | 0.7.58 | Marenich, Cramer, Truhlar 2009 |
| Nonpolar solvationSwitched solvent-accessible area, surface tension and cavitation with gradients. Areas are checked against exact sphere and spherical-cap areas (within 1 %), gradients against finite differences, and the cavitation term against exact limits of the Pierotti formula as printed in Tomasi et al. 2005 (Eqs. 81, 82, 86). No printed cavitation or surface energy is reproduced yet. | Partial | 0.7.56 | York, Karplus 1999; Tomasi et al. 2005 |
| COSMO-RSSigma profiles and potentials, activity coefficients, solvation free energies, vapour pressures and partition coefficients from COSMO segments; binary vapour-liquid and liquid-liquid equilibria and solid solubility. H, C, N, O and Cl, neutral compounds only. COSMO-RS parametrisation level not reproduced. A COSMO-SAC model core (Mullins et al. 2006) is built and checked on exact properties but not wired to the tool; no printed activity coefficient reproduced. | Partial | 0.9.5 | Klamt 1995; Klamt, Eckert 2000; Mullins et al. 2006 |
| pKa from thermodynamic cyclesAbsolute and relative pKa with stated uncertainty. | Partial | 0.7.56 | Kelly, Cramer, Truhlar 2006 |
| Redox potentialsStandard reduction potentials versus SHE or a reference couple. Printed-value check: from the printed proton solvation and formation free energies, Eq. (18), the tool reproduces the four absolute potentials of the standard hydrogen electrode in Marenich et al. 2014 Table 2 within 0.01 V. The calculated reduction potentials of Table 3 are not reproduced: only the 0.14 V shift between the 4.28 V and 4.42 V references is tested. Electron convention Unverified. | Partial | 1.2.0 | Kelly, Cramer, Truhlar 2006; Marenich et al. 2014 |
| Cluster-continuum solvation of ionsCluster-continuum scheme for the solvation free energy and pKa of ions from explicit water clusters plus a continuum, composed from your own energy, thermochemistry and solvation results. You compose the energy calls; the tool combines them. No printed value reproduced yet. | Partial | 1.9.0 | Ho, Coote 2010 |
| ElectrochemistryHydrogen electrode free energy steps against potential and pH, Pourbaix diagrams from couples with pKa values, and grand canonical electrode energies. Hydrogen-electrode steps, Pourbaix lines and grand canonical electrode energies are checked by exact algebra only; the source paper of the computational hydrogen electrode (Norskov et al. 2004) is not held. The comparison with Marenich et al. 2014 belongs to the redox-potential tool: it reproduces the absolute hydrogen-electrode potentials of Table 2 from the printed proton free energies within 0.01 V, not the calculated potentials of Table 3. No printed electrode potential is reproduced by this tool. No implicit electrolyte for periodic electrodes and no constant-potential SCF. | Partial | 1.9.0 | Marenich et al. 2014 |
| GB screening sets and nonlinear Poisson-BoltzmannSRI99 screening as the default Generalized Born set, the HCT96 SM5.4PD pair set, and the nonlinear Poisson-Boltzmann total electrostatic energy. The Srinivasan et al. 1999 screening values (H, C, N, O, P, S, Fe) and the Hawkins, Cramer, Truhlar 1996 SM5.4PD radii and pair factors equal the printed tables; other elements are refused. The nonlinear Poisson-Boltzmann energy is checked against the linear energy in the low-salt limit and by sign rules (Sharp, Honig 1990), not against a printed value. No printed GB or PB energy is reproduced yet. | Partial | 1.6.0 | |
| Generalized Born, MM/GBSA and Poisson-BoltzmannHCT, OBC1 and OBC2 Generalized Born with decomposition, MM/GBSA, and linear and nonlinear finite-difference Poisson-Boltzmann potentials. GB energies are checked against the Born formula for one ion and the Still pair formula, the HCT closed form against direct quadrature, and Poisson-Boltzmann potentials against the Born ion and the analytic sphere solutions of Tironi et al. 1995 (within 2 %); MM/GBSA by exact sum rules. No printed GB, PB or MM/GBSA energy of a molecule is reproduced yet. GBn2 and PB forces refused. | Partial | 1.4.0 | Onufriev, Bashford, Case 2004; Kollman et al. 2000 |
| SMD in organic solvents and 3D-RISMSMD with solvent descriptors you supply, and 3D-RISM solvent distributions with HNC closure. No built-in organic descriptors. 3D-RISM gives solvent distributions only, no solvation free energy. | Partial | 1.5.0 | Marenich, Cramer, Truhlar 2009 |
Printed Value, Our Value
| Quantity | Source | Printed | Ours | Result |
|---|---|---|---|---|
| Absolute Potential of the Standard Hydrogen Electrode from the Printed Proton Solvation and Formation Free Energies, Eq. (18), V | Marenich et al. 2014 Table 2, doi 10.1039/c4cp01572j | 4.44, 4.42, 4.28, 4.28 | 4.446, 4.415, 4.270, 4.270 (inputs printed to 1 kJ/mol) | Match |
Not Offered Today
- Built-in SMD descriptors for organic solvents
- 3D-RISM solvation free energies
- Poisson-Boltzmann electrolyte for periodic electrodes
- Continuum solvation with scans, transition states or IRC
- SMD optimisation and frequencies (SMD in water is energy only)
In the Chemistry Lab
Start, then Solvent effects. Choose water or a dielectric; for pKa and redox the guided flow lists the gas and solvated runs it needs and assembles the cycle.
Solvation Questions
How accurate is a computed pKa?
The cycle carries a stated uncertainty of at least 2 kcal/mol, which is more than one pKa unit. Relative pKa against a similar reference is more reliable.
Which solvents are available?
Water, dichloromethane, cyclohexane, toluene or any dielectric constant for PCM and COSMO; SMD in water, or in an organic solvent when you give its descriptors. Continuum models run energy, optimisation, frequencies and CIS, TDA, TDHF or TDDFT excited states (equilibrium linear response); SMD in water is energy only; there is no solvation with scans, transition states or IRC. Surfaces have at most 6000 elements.
Is COSMO-RS available?
Sigma profiles, activity coefficients, solvation free energies, vapour-liquid and liquid-liquid equilibria and solid solubility, for neutral compounds of H, C, N, O and Cl. It is marked Partial: the parametrisation level is not reproduced and no printed activity coefficient has been matched; a COSMO-SAC model core is built and checked on exact properties but is not yet wired to the tool. 3D-RISM gives solvent distributions only, no free energy.
See It on a Molecule of Your Own
See your own molecule optimised, its spectrum computed and the printed reference values shown beside the result.