Band decomposed charge density

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SUMMARY

The discussion centers on the concept of band decomposed charge density, particularly in relation to conduction bands in solid-state physics. It references the figure from PHYSICAL REVIEW B 78, 235430 (2008) and clarifies that conduction bands are not empty even in the ground state, especially in metals. The conversation highlights the VASP software's parameter NBMOD, which determines how charge density is calculated, with NBMOD=0 including all bands and NBMOD=-1 calculating the total charge density. This distinction is crucial for understanding charge density calculations in electronic structure theory.

PREREQUISITES
  • Understanding of band theory in solid-state physics
  • Familiarity with VASP (Vienna Ab-initio Simulation Package)
  • Knowledge of Bloch functions and electron density calculations
  • Basic concepts of conduction bands and ground state properties
NEXT STEPS
  • Research the VASP parameter settings and their implications on charge density calculations
  • Study the differences between charge density and total charge density in electronic structure calculations
  • Explore the implications of conduction band occupancy in metals
  • Review literature on band decomposed charge density, particularly in relation to PHYSICAL REVIEW B articles
USEFUL FOR

Researchers and students in condensed matter physics, computational materials scientists, and anyone involved in electronic structure calculations using VASP.

Douasing
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Hi,there are many literatures concered with band decomposed charge density(As an example,see FIG.3 in PHYSICAL REVIEW B 78, 235430 2008).
For condution band,there should not be charges or electrons when the system is in the ground state,but,those literares still show a band decomposed charge density picture,I'm very confused with that.
Douasing
 
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Do you have a link for that figure? I can find it in google, but it's not available for free.
 
Of course. The link is http://journals.aps.org/prb/pdf/10.1103/PhysRevB.78.235430
And the FiG.3 is shown as follows:
upload_2014-12-15_12-34-48.png

FIG. 3. Color online Band decomposed charge density at the Gamma
point for 13,0, 14,0, and 16,0.
 
Last edited by a moderator:
In general, the conduction band isn't empty, not even in the ground state, especially in metals. So I don't see a reason as why not to calculate charge density. The pictures you are showing is the electron density $$ |\psi|^2$$ as would result from a single Bloch function or orbital being filled. Obviously, you can plot it irrespective of whether the orbital is filled or not.
 
DrDu said:
In general, the conduction band isn't empty, not even in the ground state, especially in metals. So I don't see a reason as why not to calculate charge density. The pictures you are showing is the electron density $$ |\psi|^2$$ as would result from a single Bloch function or orbital being filled. Obviously, you can plot it irrespective of whether the orbital is filled or not.
In VASP, there is a parameter called NBMOD as follows:
NBMOD=0 : Take all bands to calculate "the charge density", even unoccupied bands are taken into account.
NBMOD=-1: Calculate the "total charge density" as usual. This is the default value if nothing else is given.
What's the difference bewteen "the charge density" and "the total charge density" ?
 

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