Potential and impurities

  • Thread starter Niles
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  • #1
Niles
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Hi

1) I have read in an article that the atoms in a lattice are at "half-filling". As I understand, this means that the chemical potential is zero. Why does "half-filling" mean since it equals that the chemical potential is zero?

2) Lets say that I place an impurity with potential U0 in my lattice. Does it make a difference whether U0 is positive or negative? What is the usual case?

Best regards and happy Easter,
Niles.
 

Answers and Replies

  • #2
kanato
415
1
1) Half filling means every site in the lattice has a single particle. Since each site can hold two particles, you are at helf filliing. The chemical potential being zero is a consequence of having a symmetric band structure and an on site energy of zero.

2) Yes it matters whether U0 is positive or negative. I think there is no usual case, it depends on what kind of model you want to study.
 
  • #3
Niles
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Thanks. Regarding #2, if I set U0>0, then it "costs" more energy to be there, right?
 
  • #4
kanato
415
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Right
 

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