How to model large atoms

In summary, quantum mechanics is used to analyze atoms and molecules, while quantum chemistry is used to understand the behavior of atoms and molecules in response to external fields.
  • #1
VVS
91
0
Hi!

One can easily analyze the Hydrogen Atom since it is a two body problem.
But how do you apply Quantum Theory to model atoms (such as iron) which are much larger and predict their behaviour in an environment?
My guess is that you use statistical mechanics, but I only just started a course and it is basically limited to heat.

thank you
VVS
 
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  • #2
The first approach is still a two-body problem. Afterwards, interactions between the electrons can be taken into account. To describe the state of the electrons and bonds in a material, this is pure quantum mechanics.
If you want to describe things like heat, you don't have to care about those details, you take the "output" of quantum mechanics (crystal structure, energy bands and so on) and apply statistical mechanics to it.
 
  • #3
Hi mfb!
Thanks for your answer.
Basically I want to evaluate the effect of electric fields, magnetic fields and magnetic vector potentials on the properties of Iron in haemoglobin.
How do I go about this?
 
  • #4
I guess that will need some protein folding software if you expect effects - the fields influence the whole thing, not just a single small atom inside.
 
  • #5
By the way, I think we analyze the Hydrogen atom by quantum mechanics is a one body problem, because we assume the nuclear is fixed, and it just provide a potential to the atom system, but in the real physics we should also use a wave-function to describe the nuclear
 
  • #6
Usually the two-body problem is reduced to a 1-body problem with a reduced mass, so both electron and nucleus are taken into account. The other degrees of freedom of the two-body system correspond to a total motion of the atom.
 
  • #7
OP, real atoms (and molecules) are handled with quantum chemistry software. Such programs (e.g., Molpro, Orca) can solve the many-body Schrödinger equations in various approximations to determine the quantitative behavior of the electrons, including their response to external fields. For Iron atoms, for example, you would employ approximations like Hartree-Fock and CCSD(T) (a coupled cluster method) or Multi-configuration self consistent field (MCSCF) and mutli-reference configuration interaction (MRCI), depending on the application.

Understanding and using such approximations (correctly) is not easy, and normally requires some background reading in many-body quantum mechanics and quantum chemistry.
 

1. How do you model large atoms?

Modeling large atoms requires advanced computational techniques and algorithms. The most common method is the quantum mechanical approach, which uses mathematical equations to describe the behavior of electrons and their interactions with the nucleus. This allows us to simulate the behavior of large atoms and predict their properties.

2. What factors affect the accuracy of large atom models?

The accuracy of large atom models is affected by various factors, such as the complexity of the atom's electronic structure, the precision of the computational methods used, and the accuracy of input data. Additionally, the accuracy can also be affected by the limitations of the model itself, such as the assumptions made and the level of approximation used.

3. Can large atom models be used to predict chemical reactions?

Yes, large atom models can be used to predict chemical reactions. By simulating the interactions between atoms and molecules, we can gain insights into the underlying mechanisms of chemical reactions and predict the products and rates of reactions. However, the accuracy of these predictions depends on the complexity of the reaction and the level of approximation used in the model.

4. How do you validate large atom models?

Validation of large atom models involves comparing the results of the model with experimental data or with more accurate theoretical calculations. This helps to ensure that the model is reliable and can accurately predict the properties or behaviors of the atom being studied. Additionally, performing sensitivity analyses and benchmarking the model against known systems can also help to validate the model.

5. Can large atom models be used to design new materials?

Yes, large atom models can be used in materials design. By simulating the properties and behavior of atoms at the atomic level, we can gain insights into the structure and properties of materials and predict how they will behave under different conditions. This allows for the design of new materials with specific properties and functionalities.

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