Solid-state physics studies how macroscopic properties of solids (mechanical, electrical, optical, etc.) result from their microscopic structure. It usually deals with the scale where quantum properties of the particles are substantial.

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Simple examples for exchange and correlation

Is there an easy, in the best case intuitive, explanation of the difference of exchange and correlation? Is there a simple way to distinguish whether a certain contribution is due to exchange or ...
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Do I understand measurement of dispersion relation in a solid correctly?

I'm currently doing an introduction to solid state physics course and have a quick question about measurement of the dispersion relation of phonons in a solid: The way I understood it is the ...
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Is there a difference in binding energy between a regular material and a doped one?

Say Silicon and boron doped silicon. Would the doping affect the binding energy? Could I see this in an XPS spectra?
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205 views

More physical explanation of impurity energy levels in a doped semiconductor?

I'm reading about doped semiconductors in Ashcroft and Mermin. They tell you that when donor impurities are added to a semiconductor, their energy level $E_d$ is just slightly below the conduction ...
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176 views

Average number of spin up particles

In a paramagnetic system, where $N = N_\uparrow + N_\downarrow$ is fixed, how does one calculate the average number of spin-up particles $\langle N_\uparrow \rangle$? You can assume we have the ...
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55 views

Long range repulsion in anomalous solids

As far as I know things like rocks, walls, rubber balls, polished tables etc. exert a short range repulsive force on other everyday objects that is responsible for hardness, softness, collisions, ...
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Is there a derivation of all possible Bravais lattices in 2D and 3D?

Do any of you know a (possibly elegant) derivation of all possible Bravais Lattice and the Crystallographic Group of Lattices in 2 and 3 dimensions? Group theory /abstract nonsense approaches are ...
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361 views

How to demonstrate that there are just 14 types of Bravais lattice?

Is it possible to demonstrate that there are just 14 types of Bravais lattice without the knowledge of group theory?
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When is the Fermi surface a surface of constant mean curvature?

Fermi surfaces are surfaces of constant energy in reciprocal space. They provide information about the properties of a material in solid state physics. Constant mean curvature surfaces are a superset ...
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What is the “center of gravity of a band”?

It seems there is a term called "center of gravity of a band" in solid state physics or chemistry which I'm confused about. Could anyone give a formal definition of the term or point to some reference ...
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Equal time displacement correlation functions and their physical interpretation?

Displacement correlation functions in question are within harmonic approximation and are derived for example in: A. Maradudin, Dynamical properties of solids 1, 1 (1974). Maradudin says about the ...
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127 views

Sommerfeld results & van Hove singularities

According to Sommerfeld the derivative of the density of states $g'(\varepsilon)$ apears in several thermodynamic quantities. Will this also be the case if one use the correct dispersion relation of ...
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46 views

Residual symmetries of the superposition of two fcc lattices

Fcc lattices are Bravais lattices and so are invariant under a set of discrete translations plus inversions over the 3 axis ($x\rightarrow -x$,$y\rightarrow -y$,$z\rightarrow -z$). When one superposes ...
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How to derive the divergence leading to Kohn anomalies?

I'm trying to understand the mathematical derivation given in the book "A Quantum Approach to Condensed Matter Physics" on page 215 (see 1), for explaining how the phonon-energy perturbed by ...
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139 views

Decomposition of elastic constants of a crystalline material

I have performed a calculation the tensor of elastic constants (or stiffness tensor) for a given crystalline material. From there, I calculated various elastic properties, such as Young’s modulus, ...
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390 views

Electron Fermi gas

My question is about 2-dimensional Fermi gas of electrons. What is magnetic susceptibility when $T<<T_F$ (where $T_F$ is Fermi Temperature) and, What is the ratio between Pauli and Curie ...
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560 views

Evaluation of band gap from transmittance

How can I evaluate the band gap of my ZnO thin film. Thickness=d=80 nm I’m aware of alpha=-1/d*log(T) But I can’t fit a line to my data. And: How can I smoothen my data on about 346 nm? Do you have ...
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439 views

Fermi level in disordered amorphous and/or organic semiconductors

So, the Fermi level in crystals is pretty easy to understand. Been using it and talking about it in terms of the highest occupied level forever. However, I'm now reading about disordered systems. A ...
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How to get DOS of Van Hove singularity using quadratic dispersion relation

Take 2D case for example. We can first get the area in momentum space for all $k$ that satisfy $E_0<E(k)<E $, say $S(E)$. And the density of state (DOS) is $\rho(E)=\frac{\partial S(E)}{\partial ...
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Exercises about solid state physics ( free electron, tight binding approximations)

I'm doing a (first) course in solid state physics following the book of Ashcroft/Mermin , the classes are quite theoretical and we have practically no examples. The problem that I'm having is that I ...
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26 views

How to calculate the dispersion relation of graphene?

Graphene is a well investigated two-dimensional material in nano-physics. My teacher asked me to calculate its phonon dispersion with interactions between the first and second nearest neighbors, both ...
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27 views

Specific Heat of Liquid Helium

At the lambda point, the specific heat of Liquid Helium diverges. After searching for a curve, I've found only measured curves. Is there a theoretical curve for this transition?
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30 views

Relation between energy band gap and atomic number

Is there any relation between energy band gap in group4 elements and their atomic numbers? It might be just a trivial observation but I noticed How from Carbon to Germanium the band gap went from ...
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27 views

Klein paradox in graphene

When considering the Klein paradox in graphene Katsnelson, Novoselov and Geim introduce a potential barrier (see http://www.nature.com/nphys/journal/v2/n9/full/nphys384.html). But I cannot understand ...
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Do hexagonal structure parameters vary with peaks?

Do the values of lattice constants $a$ vary with different peaks for same structure, as well for $c$, or should there be the same values for $a$ at different planes? Is there any special software ...
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Scattering and form factor

In Introductory Nuclear Physics by Krane (there's a PDF online), it is mentioned electron scattering on the nucleus to get a picture of the latter's shape, e.g., its radius. It is said the probability ...
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what is the difference between mictomagnetism and spin glass?

What is the difference between mictomagnetism and spin glasses? I mean what are the distinguishing characteristics of them which makes them separate?
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Combining a p and n type semiconductor

According to my textbook, when a p and n type semiconductor combine the following happens: Electrons from the n type semiconductor will migrate into the p-type semiconductor at the junction (so the ...
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23 views

Relation between Fourier Transform of potential $v(x)$ and |r| in Born approximation

I'm doing an exercise about Kronnig Penny model and I'm asked to do the following: If $t=|t|e^{i\delta}$ and $r=\pm i|r|e^{i\delta}$ are respectively the transmission and reflection coefficients. And ...
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29 views

Why do some materials have a negative coefficient of thermal expansion in all directions?

Those materials are especially ceramic-glasses. I've found some studies about how does it happens in one dimension (for example a nanocrystalline has a silica helix that works like twisting spring, ...
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Ground State energy as a function of $N$ and $B$, $E_0(N,B)$

The one-particle Hamiltonian is given by: $$\hat{H}=\frac{1}{2m}\left(p+\frac{e}{c}A\right)^2$$ where $p=\hbar\vec{k}$ with $e > 0$ and vector potential $A=(0,x,0)B$, such $B=\triangledown ...
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Spring limitation

Is there any limitation in acceleration and frequency of a spring. Please, imagine a horizontal spring with an object of mass $m$ attached in the free side and the friction is neglected. ...
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30 views

What is the justification for the minimum image convention in periodic boundary condition?

As the distance between first particle-second particle and first particle-image of the second particle are not same. How is it justified to use the distance from the nearest image to compute ...
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23 views

What is the work-function of a monolayer metal on a substrate with charge redistribution at the interface?

The work-function on subsrate/metal with nm thick (or above) metal layer generally reveal the intrinsic work-funtion of bulk metal. But what if there is a monolayer thick metal, and there is charge ...
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Magnetic anisotropy

Magnetic anisotropy is a prerequisite for hysteresis in ferromagnets: without it, a ferromagnet is superparamagnetic. Is this correct? I think even magnetically isotropic material can have hysteresis ...
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28 views

What is the difference between finite displacement and linear response for calculating vibrational properties?

I see these concepts appearing in the context of calculating phonons and other vibrational properties, but I can't find a concrete explanation of the differences between linear response (DFPT) and the ...
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32 views

Textbook on 2D Crystals

I've become interested in $2$D crystals, and in particular graphene. I'm looking for a textbook which covers graphene -- possibly as part of a course on solid state theory -- for undergraduates. For ...
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Is there a list of (the solid state version of) electron affinities?

I'm doing some energy band diagram analysis for a few scenarios, and I need the Electron affinity as defined in solid state physics for a few materials. Note that this is different than the one taught ...
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Relation between surface carrier density and Fermi level?

Can anyone tell me the relation between Fermi level and $n_\mathrm{s}$ (surface carrier density ) at temperature $T$? Are electrons are distributed in the two-dimensional case?
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45 views

In which direction along a GaN (wurtzite) crystal are only Ga atoms being observed?

So, if you have an electron microscope image of a GaN crystal, and that it shows only white dots which represent Ga atoms. No nitrogen atoms are seen in the image. Along which direction is this ...
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15 views

What is a re-entrant energy contour in a band structure?

I have a question involving band structure in solids. What does it mean to say that an energy contour in a band structure is re-entrant? Herbert Kromer uses this term in: H. Kromer, Phys. Rev. 109, ...
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the derivation of the “spectral function”

My question is from this article at page 8, from eq21 to eq 25. http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.34.5179&rep=rep1&type=pdf That is, I got stuck while deriving ...
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Normal modes and lattice symmetry

In chapter 22 of Ashcroft & Mermin, it says: Theorem: any transformation that leaves $\mathbf{k}$ and the lattice invariant must transform one normal mode with wave-vector $\mathbf{k}$ to ...
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Hamiltonian for semiconductor

I was wondering which terms we need in a semiconductor Hamiltonian where no transition between the valence and conduction band occur? First we would have a term describing the energy of the full ...
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Capacitor of Pearson–Anson oscillator

I was calculating capacitance of Pearson–Anson oscillator and comparing with simple RC circuit but I get two different values. They have significant difference. I am not clear why do they have. Could ...
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37 views

Integrals in tight-binding method

In the tight-binding method, as e.g. described in Ashcroft and Mermin one need to solve a few integrals in order to proceed. For example for the overlap between an orbital situated at two different ...
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54 views

How to derive De Haas–van Alphen effect?

I was reading Solid State Physics by Kittel and they manage to derive De Haas–van Alphen effect by invoking the Bohr-Sommerfeld model. This feels unsatisfactory to me. Can someone derive this using ...
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34 views

Is it possible to get the (Pauli) repulsive term in the Lennard-Jones potential from theoretical considerations?

Title says it: Is it possible to get the form of the (Pauli) repulsive term in the Lennard-Jones potential from theoretical considerations, or is it purely found experimentally through fits?
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How does the saturation current of a heterojunction depend on on the band gap difference?

In my textbook, they demonstrate that, for a regular n-Si/p-Si pn junction, the electron saturation current density (it's pretty much the same for the holes, but with hole properties instead of ...
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Reciprocal to determine Miller indices

If we know the reciprocal space basis of a BCC lattice \begin{align}b_1=\frac{2\pi}{a}(\vec{x}+\vec{y}),b_2=\frac{2\pi}{a}(\vec{z}+\vec{y}),b_3=\frac{2\pi}{a}(\vec{x}+\vec{z})\end{align} how do we ...