Materials Chem Band Structure

What is k?

a parameter that leads to different energy levels

range of unique k values is called the…

first Brillouin zone

graph of E(k) vs. k

band structure

at k=0, all wave functions are…

in phase

at k=π/a, all wave functions are…

out of phase

band width

difference in energy between highest and lowest levels in the band (difference between bonding and antibonding levels)

greater orbital overlap means…

greater band width

Which type of orbital interactions have the greatest band width?

sigma

As a standard, we always show bonding interactions as happening in the…

z-direction

head to head interactions

sigma interactions

parallel interactions

pi interactions

face to face interactions

delta interactions

What is COOP?

an overlap-population-weighted density of states

What does a COOP graph show?

antibonding DOS on the left and bonding DOS on the right

Fermi Level

hypothetical energy level, such that at thermodynamic equilibrium, this energy level would have a 50% probability of being occupied at any given time

Where is the Fermi level hypothetically located

between HOMO and LUMO

Fermi level is the ___ between occupied and unoccupied energy levels.

cutoff

valence band

highest occupied band

conduction band

lowest empty band

Where is the fermi level in a metal?

located through a band to produce a partially filled band

Where is the fermi level in a semimetal?

band gap is zero (zero energy gap between filled bands and empty bands)

Where is the fermi level in a semiconductor/insulator?

energy gap between filled bands and empty bands (as the gap becomes larger, the material becomes a poor conductor of electricity)