Understanding Slater Determinants Using He 1s2 & 1s12s1

In summary, Slater determinants are used for identical fermions in quantum mechanics and represent the wave function for these particles as anti-symmetric. They make use of the notation of a determinant, which has a mathematical meaning in other areas such as integration. The construction of a Slater determinant for electrons in an atom can be done using either rows or columns, as the determinant is the same regardless of transposition.
  • #1
fricke
39
3
I am really really really confused how to read and construct Slater determinants :(
Can someone please explain it using He at the ground state (1s2) and He at excited state (1s12s1) ?
 
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  • #2
The basic idea is that the wave function for identical fermions must be anti-symmetric.

The Slater determinant simply makes use of the definition of a determinant to notate the above idea.

https://en.wikipedia.org/wiki/Determinant

(For quantum mechanics, you can think of it as the determinant as just notation and not otherwise meaningful. However, in mathematics or probability, the determinant has the meaning of an area or a volume: http://mathinsight.org/relationship_determinants_area_volume. It is very useful in the change of variables formula in integration using Jacobians, which makes sense because the integral is a sum over area or volume elements: https://www.stat.wisc.edu/courses/st309-larget/jacobian.pdf.)
 
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  • #3
atyy said:
For quantum mechanics, you can think of it as the determinant as just notation and not otherwise meaningful
I understand how to calculate the determinant. But how to construct determinant for electrons spin in an atom?
 
  • #4
fricke said:
I understand how to calculate the determinant. But how to construct determinant for electrons spin in an atom?

http://jila.colorado.edu/Chem4541/Indistinguishable%20particles,%20Pauli%20Principle,%20Slater%20determinants%20p%2091-98.pdf
 
  • #5
atyy said:
http://jila.colorado.edu/Chem4541/Indistinguishable%20particles,%20Pauli%20Principle,%20Slater%20determinants%20p%2091-98.pdf
thank you!
I have another question.
Prof taught us one row represents one electron, so each electron is represented in a row in Slater Determinant. But when I googled it, some represents one electron in one column (not in one row!). Mathematically, it seems to be not wrong (since I didn't do any calculation to prove these two are the same) but how can representing electrons in column rather than row be the same in quantum electron spin?
 
  • #6
fricke said:
Prof taught us one row represents one electron, so each electron is represented in a row in Slater Determinant. But when I googled it, some represents one electron in one column (not in one row!). Mathematically, it seems to be not wrong (since I didn't do any calculation to prove these two are the same) but how can representing electrons in column rather than row be the same in quantum electron spin?

I'm not entirely sure of this part, but I believe it is because the determinant is the same whether rows and columns are transposed.

https://www.khanacademy.org/math/li...-determinant-of-transpose?_escaped_fragment_=

But you should check the wave function is the same whether you write each electron as a row or a column.
 
  • #7
atyy said:
I'm not entirely sure of this part, but I believe it is because the determinant is the same whether rows and columns are transposed.

https://www.khanacademy.org/math/li...-determinant-of-transpose?_escaped_fragment_=

But you should check the wave function is the same whether you write each electron as a row or a column.
thank you. I have found out a really easy way to construct Slater determinant for electron spin of an atom :D
 
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Related to Understanding Slater Determinants Using He 1s2 & 1s12s1

1. What is a Slater determinant?

A Slater determinant is a mathematical expression used to describe the quantum state of a multi-electron system, such as an atom or molecule. It is a combination of single-electron wavefunctions, known as orbitals, that takes into account the antisymmetric nature of quantum particles.

2. How is the He 1s2 orbital represented in a Slater determinant?

The He 1s2 orbital is represented by the product of two single-electron wavefunctions, one for each electron. These wavefunctions are typically denoted as ψ1s(x1, y1, z1) and ψ1s(x2, y2, z2), where x, y, and z represent the coordinates of each electron.

3. How does the 1s12s1 Slater determinant differ from the He 1s2 orbital?

The 1s12s1 Slater determinant includes an additional orbital, the 1s orbital for the second electron. This means that the wavefunction for the second electron, ψ1s(x2, y2, z2), is now included in the determinant, resulting in a more accurate description of the system's quantum state.

4. How do Slater determinants help us to understand the electronic structure of atoms?

Slater determinants provide a way to describe the quantum state of a multi-electron system, such as an atom, by taking into account the antisymmetric nature of quantum particles. This allows us to understand the arrangement and energy levels of electrons in an atom, which is crucial for understanding the chemical and physical properties of elements.

5. Are Slater determinants the only method for describing multi-electron systems?

No, there are other methods for describing multi-electron systems, such as Hartree-Fock theory and configuration interaction. However, Slater determinants are a commonly used and effective method for understanding and describing the electronic structure of atoms and molecules.

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