13 votes

Is there a way to obtain solution-phase dielectric constants?

It's possible to estimate solution-phase dielectric constant from a molecular dynamics simulation using this formula: $$\epsilon_{r} = 1 + \frac{4\pi}{3Vk_{B}T}(\langle \mathbf{P}^{2} \rangle - \...
Mithridates the Great's user avatar
12 votes

Why are ions in water not paired?

There actually is ion pairing in aqueous solutions, but the concentration of paired ions is usually much lower than fully dissociated ions. You should also take into account that typical ...
Stephen's user avatar
  • 721
9 votes

Calculate Redox Potential

There are several protocols. Since you mention that you're mostly looking for trends, I'll give the faster method, e.g. by Jason Gilmore: "Expanding and Testing a Computational Method for ...
Geoff Hutchison's user avatar
6 votes

How to calculate sigma-profile using COSMO/RS and Gaussian 16?

Gaussian itself doesn't have any way of computing sigma-profiles on its own. As you noticed, it has the scrf=COSMORS keyword, but this just produces a file that is ...
Tyberius's user avatar
  • 15.5k
5 votes

How to build up a supercell for explicit solvent system?

1. Using ASE GUI You can utilize ase gui to build supercell manually. Open ASE GUI window with two molecules (for example ase gui emim.xyz bf4.xyz). Then create new ...
mjhong's user avatar
  • 71
4 votes

What are the methods for calculating solvation effects in free energies and how do they compare?

Just throwing a couple of ideas out there: (i) Perform a free energy perturbation or potential of mean force calculation as available in typical classical MD setups. For known salt systems in water, ...
gogo's user avatar
  • 1,247
3 votes

What are the types of solvation models?

COSMO Name: COSMO = Conductor-like Screening Model. Type: Implicit Dielectric continuum model First appearance: 1993 by Klamt & Schüürmann, COSMO: a new approach to dielectric screening in ...
I have no free time anymore's user avatar
2 votes

Why are ions in water not paired?

It's the entropy – suggested reading, ET Jaynes: Information theory and statistical mechanics. For the same reason, water vapour exists already at room temperatur (~1 mol/m³, TU Wien: Vapor Pressure ...
Rainald62's user avatar
  • 121
1 vote

How to build up a supercell for explicit solvent system?

You might find the Avogadro software (old v1.20) useful for this work. You can create a specified cell (Crystallography>>Add unit cell) and copy and paste the structures you might already have (...
Hashan Peiris's user avatar
1 vote

Compute solvation energies with (ESM) RISM-SCF

There are certain quantities that become poorly defined when you have a charged system. This could be what the author was referring to if you are studying the adsorption of ions or studying adsorption ...
Stephen's user avatar
  • 721

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