Structure Definition and 1000 Threads

I'm teaching myself how to do DFT for my master's project, where I want to use it for calculating band structures for different heterostructures. Now to learn DFT I am on one hand reading a book on the basic theory, on the other hand using different freeware packages to try and calculate the...

I know how to calculate band structure of two dimensionaI sheets by tight binding. I am looking for a reference to learn thoroughly how to calculate band structure of 2d-ribbons (Graphene nanoribbon, Silicene nanoribbon,...) using tight binding method. Could anyone please help me?

The commutation relations for the ##\mathfrak{so(n)}## Lie algebra is:##([A_{ij},A_{mn}])_{st} = -i(A_{j[m}\delta_{n]i}-A_{i[m}\delta_{n]j})_{st}##.where the generators ##(A_{ab})_{st}## of the ##\mathfrak{so(n)}## Lie algebra are given by:##(A_{ab})_{st} =...

I have some qualitative questions about the relation between band structure, density of states, and Fermi energy (or Fermi level). 1) Say you have a given electronic band structure (energy as a function of k) obtained by any method. How do you relate this to the Fermi energy (or Fermi level) ...

Homework Statement I am running CASTEP DFT software to simulate pristine graphene, and am unsuccessful in obtaining the trademark zero band gap at the k-point as reported in numerous papers to date. Any assistance would be greatly appreciated as the subject is very new but I am keen to push...

Hi I have been drawing pi bands, silicon nanoribbons. But I can't draw sigma bands. Can help me for plotting sigma bands, silicon nanoribbons in Matlab.

I almost "get" it, but not quite. Can someone help? Here is my current understanding. Say you solve the Kronig-Penny model. You find that you get bands of N closely spaced energy levels, with large gaps between them. Under normal conditions, electrons fill the band to some level (let's say we...

Homework Statement Let (S,\cdot ) be an algebraic structure where the operation \cdot is associative and commutative and also the following axiom is satisfied: \forall x,y\in S,\exists z\in S: zx = y\ \ (1) Prove that if for every a,b,c\in S, ac = bc, then a=b. Homework EquationsThe Attempt...

I've been reading about the Dirac equation, and most authors eventually make some statement to the effect that the fact of spin and antiparticles falling out of the equation reflects a deep connection to the structure of spacetime. Is the implication that the math requires four particle states...

The structure factor in solid state physics (https://en.wikipedia.org/wiki/Structure_factor) apparently gives information on the scattered ray from a lattice. How exactly does it do that? Does a structure factor of zero at certain points imply that rays cannot be scattered in those...

Hello! I've been trying to figure out what the most stable structure of inositol is, but I keep running into conflicting information. I'm not sure whether the most stable conformation is the myo-inositol form or the scyllo-inositol. All of the stereoisomers can be seen on wikipedia at this link...

I have done my research and understand why quantum tunneling happens and I fully understand that there is no point at which the particle examined ever actually intersects with the barrier. The only part at which my knowledge feels fuzzy is at the mathematic equations. If a large object, such as...

Homework Statement Calculate the static structure factor for noninteracting fermions S(\vec{q})=\frac{1}{N}\langle \phi_0|\hat{n}_{\vec{q}}\hat{n}_{-\vec{q}} | \phi_0\rangle where \hat{n}_\vec{q}=\sum_{\vec{k},\sigma} a^\dagger_{\vec{k}\sigma}a_{\vec{k}+\vec{q}\sigma} is the particle density...

Homework Statement If we take the average radius of the electron wave function in the ground state of hydrogen to be the Bohr radius, calculate the average potential energy of the electron due to the Coulomb interaction with the nucleus. State answer in eV. Homework Equations I think the...

Do any band structure (in absence of any external field) in general, is symmetric with respect to k? In other words, do we always have E(k)=E(-k).

Does "quasi-two-dimensional structure" of cuperates mean that a cuperate material is regarded as a stack of thin layers and there is almost no structural interaction among the layers? BTW, is Meissner effect meaningfual to a thin film superconducting material? Thank you.

Is the claim that all definitions are biconditionals, true? Is the converse statement true as well, that all biconditionals are defintions?

Take a prime order cyclic group. I want to take that as the additive group of a finite field. Since every finite field of the same order is isomorphic to one another, does the isomorphism define a multiplicative group structure on my cyclic group elements?

Hi I have a few questions that I have been working on but I don't get the right answer. After drawing the Lewis dot structure of HOClO2, pick the incorrect statement of the following. A. The oxygen bonded to the hydrogen has two lone pairs B. the oxygens not bonded to hydrogen have three lone...

Hi All A mathematical structure : is A set with an Object ( structure ) and there are generally two types of mathematical structure , which are algebraic structure and space ( geometric structure ) Eaxmples of algebraic structure are rings , fields , modules vector spaces ... act Examples of...

Homework Statement I have the following code which manipulates with basics of structures. There are function like reading and sorting data from structures. Now, I don't know how to write a function that reads name and surname of an author of a book, and then prints data about books that are...

Trying to reverse-calculate an equation to achieve one of the original variables when not present. 1) You have a number... A (which is always a positive number) 2) A is multiplied by 1.75% 3) This result is then added to A, and the resulting sum being B, i.e. (A x 0.0175) + A = B In my...

I just saw the following news and thought this could have quite an impact on our current models and views of the Universe: The GRBs that make up the newly discovered ring were observed using a variety of space- and ground-based observatories (the sample is listed in the Gamma Ray Burst Online...

Who can help me in writing the following program: phase(i) = exp(1i*dot(k(:,index),R(:,i))) This gives you the phase you're going to multiply with the hopping parameter. You'd have to write a loop that runs from i = 1:3 in order to multiply each contribution to the hopping parameter such that...

I am in the final stages of the project I've been working on: Taking a Dynkin diagram and deriving the structure factors for the Lie algebra it represents. Yay me! However. I am confident in my work but it would still be really nice to be able to check them. Does anyone know where to find a...

Simpel question: does an atom consists of matter and charge? Yes/no?? If no Then what?

Homework Statement Calculate the surface density (planar density) of the Silicon diamond structure in the [1 0 0],[1 1 0],[1 1 1] planes. Given a = 5.431 A (latice constant) Hint: For the (111) plane, it should help you to think of the diamond lattice as two interpenetrating FCC lattices.2...

Hello. I use a MC12079 as UHF divider by 256. Unfortunately this IC was oscillating at about 10 MHz. To correct this problem I insert a 47 k resistor between non inverting input and Gnd as Inverting input is used for signal to divide. It works, but I would like to know if this can have unwanted...

Hello everyone! I’m using APDL to simulate the behavior of a specimen in tension with a sandwich structure made of honeycomb and glass fiber. It was modeled in CATIA V5 and exported to APDL in a parasolid file. Only a half of the structure has been modeled because of symmetry condition. NOTE...

Dear forum people I consider four atomic orbitals of the silicon atom: s, px , py and pz , thus Hi,j is a 4*4 matrix. Hi,i is the expression of the diagonal matrix and Hi,j is the expression off-diagonal matrix where the expression for Hi,i and Hi,j is attached. But I can not calculate the...

Dear forum people I consider four atomic orbitals of the silicon atom: s, px , py and pz , thus Hi,j is a 4*4 matrix. Hi,i is the expression of the diagonal matrix and Hi,j is the expression off-diagonal matrix where the expression for Hi,i and Hi,j is attached. But I can not calculate the...

Dear forum people, I know that electronic properties silicene is the same graphene but i can not figure out how can I plot band strcture silicene. I want to plot that in the following path: K→Γ→M→K

Homework Statement Dear forum people, I know that electronic properties silicene is the same graphene but i can not figure out how can I plot band structure silicene. I want to plot that in the following path: K→Γ→M→K

Can anyone explain to me why a bimorph has a metal in between the two piezo-layers?

This EJP paper is open access, so you should be able to read it. The conclusion isn't unexpected, because having a "scaffolding" to guide a student through a problem is almost like hand-holding without an instructor being there. I've used this type of questions during quizzes and maybe even...

Homework Statement A transition happens for ##\lambda = 494nm## in the Cesium ions (##^133 Cs##) between a term in the ##5p^5 6s## configuration and term in the ##5p^5 6p## configuration. Five components are observed with the following energies (relative to the transition of least energy): 0...

I modeled honeycomb core and face sheet seperately now i want to add or glue them to make a sandwich but it shows error so how can i join them.anyone please

In solid state chemistry, what's a normal spinal structure? I came across a question about it and I couldn't find any credible answers.

Homework Statement The polyacetylene chain is a 1D chain of Carbon atoms with single bonds and double bonds in succession. Spacing for single bond is ##a_s = 0.144~nm## and spacing for double bond is ##a_d = 0.136~nm##. Describe the structure using a "lattice" and a "basis". Sketch the...

I'm getting confused with the type of bonding (1) between the nucleotides and (2) between the nucleotide and the "sugar phosphate backbone". This diagram: http://tigger.uic.edu/classes/phys/phys461/phys450/ANJUM04/DNA_helix.jpg Shows hydrogen bonds between the nucleotide bases. But then Wiki...

Hi, I tried to find design regulations/codes that specify relations between bolt diameter/bolt length against connected plate thicknesses. I couldn't find that in Eurocodes 3. Can someone help me with info where to find those regulations ? Example: can we connect 5 mm plates using M24 ? or...

Hi, folk~ I fabricated bimorph piezoelectric shear stress sensors. When air flow applied, there were resonant frequency shifts to left side (decreasing) and impedance decrement in resonant frequency as well . So even though I am suspecting that kinds of results as because of damping effect...

...r than 1? This is the slide we have been given in class So what on Earth would the structure of PA, PC and PE be? I understand the closer to 1 it would be a bilayer so PC is likey a bilayer but can't understand what the others would be from this slide, does anyone have any ideas?

I'm considering using OneDrive for business as a part of Office 365. What I'm unsure about is how to use it exactly. What I need it for is simply as a way of accessing my files and folders in the File Explorer. What I don't get is this sync-business I keep reading about. If the only thought...

hi everyone I found out that graphite carbon conduct just in one side if there is anyone who can inform me how is the structure of this material?

The main result of thermodynamics is that if you have a place that is hot and another place that is colder, you can operate a heat engine by absorbing heat from the hot place and dumping it in the cold place, extracting some useful work in the process. It gives you a way to calculate the...

I just learned how to get a tight-binding dispersion for graphene. But i can not figure out how can I plot that. I want to plot that in the following path: Γ→K→M→Γ I would be appreciated if could some one give me a hand on my problem. thanks for alot.

Hi there, I have a metric with g_{rr}=\frac{1}{r^2-2cr}. From this it is clear there exist coordinate singularities at r=0 and r=2c. I believe that the outer horizon is the event horizon and the inner horizon is a Cauchy horizon. However, I do not know what I need to do in order to prove that...

From the ψ2 vs r graph (i.e probability of finding an electron vs distance from nucleus graph), there are no nodes for 1s orbital while there is a node in the 2s orbital graph.But they have similar structures right? Then why is there a difference in finding the probability of finding an...

Hello everyone! The electronic structure of CNT is discussed on the basis of band structure of graphene. Graphene has a linear dispersion relation: E = h_cut vF |k| where k is the 2D wavevector and vF is the Fermi velocity. CNTs are macroscopic along the axis but have a circumference of atomic...