intermolecular interactions between charged particles

Hi dear all,

I have a question about modeling of intermolecular forces in molecular dynamics:

I have seen in many papers that ion-ion or ion-dipole interactions are modeled via a potential containing a Lennard-Jones term and a coulomb one. But as we know, the attractive part of a Lennard-Jones potential models the London dispersion interactions between two instantaneously induced dipoles. The question is that is there any London dispersion forces or any other attractive forces expect the electrostatic ones between two charged particles to justify the usage of this potential for ion-ion interactions? What is the physical meaning of depth of the potential well for the potential defined between two ions dissolved in a solvent?

Is it not more logical to use the hard sphere potential indeed the LJ term?

Thanks in advance for your answers

Hi dear all,

I have a question about modeling of intermolecular forces in molecular
dynamics:

I have seen in many papers that ion-ion or ion-dipole interactions are
modeled via a potential containing a Lennard-Jones term and a coulomb one.
But as we know, the attractive part of a Lennard-Jones potential models the
London dispersion interactions between two instantaneously induced dipoles.

the lennard-jones potential has more purposes than modeling dispersion
interactions.

The question is that is there any London dispersion forces or any other
attractive forces expect the electrostatic ones between two charged
particles to justify the usage of this potential for ion-ion interactions?

yes, not to mention that there are lots of publications discussing the
validity of such parameterizations and comparing them to experimental
results.

What is the physical meaning of depth of the potential well for the
potential defined between two ions dissolved in a solvent?

which potential? are those ions of equal or opposite sign?
in general, you are looking at

Is it not more logical to use the hard sphere potential indeed the LJ term?

no. atoms and ions are not "hard", but somewhat "soft and squishy".
this is particularly true for anions of molecules and heavier
elements. apart from that, hard spheres have lots of challenges when
modeled with a conventional classical MD code.

Thanks in advance for your answers

please note, that this mailing list is not the "lammps school for
learning MD". the questions you have asked are all issues that are
unrelated to a particular MD code and discussed in the relevant
literature and text books. the primary person to discuss such matters
with is your adviser or a person designated by your adviser to
instruct you in MD basics.

axel.