Hello I am new to molecular dynamics simulations. I am trying to calculate the chemical potential for iron and phosphorus to do some grand canonical monte carlo simulations. Please help me. Thank you very much in advance.
Using thermodynamic definitions, chemical potentials can be calculated.
dU= TdS-PdV+ ∑µidNi
µi = (δU/δNi)S,V, N J≠I = (δU/δNi)T,P, N J≠I
dG= ∑i=1 n µidNi
then use the gibbs dhuem equation to feed your value for B and A components(Iron and Phosphorus) with no. of mole to crack chemical potential values.
where dU is the infinitesimal change of internal energy U, dS the infinitesimal change of entropy S, and dV is the infinitesimal change of volume V for a thermodynamic system in thermal equilibrium, and dNi is the infinitesimal change of particle number Ni of species i as particles are added or subtracted. T is absolute temperature, S is entropy, P is pressure, and V is volume. Other work terms, such as those involving electric, magnetic or gravitational fields may be added. dU for differential relation of dG could be used.
Other ways you can use electrochemical, internal, external, and total chemical potential, ideal vs. non ideal solution approach if you know the temperature values. Feed the values in dynamic simulations.
If you want to calculate at electron in solid level, then use physics principles to use ionization potentials and electron affinity values of iron and phosphorus to calculate the potential using formula, _IP+EA/2
Hope it work out for you.
Ashish
I don't understand your question. If you are simulating a grand canonical ensemble then you have your temperature and chemical potential fixed. If you are looking for a specific chemical potential value to maintaining in your simulation, then you should check your conditions for this kind of atoms or you can look for quantum chemical simulations to get the partition functions at your conditions. With this partition functions you can calculate the chemical potential but again, you have to check your conditions.
I agree with the previous two answers. We know the chemical potentials of Fe and P (see the CRC Chem Physics Handbook or Lange's Handbook of Chemistry). If you are attempting to replicate and/or utilize these through molecular modeling, then you want to "tune" the software to match the known behavior, which depends on the software. It can be quite a trick to get software to reproduce desired behavior. A good reference is "Perturbation Theories for the Thermodynamic Properties of Fluids and Solids," by J. R. Solana, from CRC Press.
- Badges
- Science topic