Structure Definition and 1000 Threads

Hello, I was building some test crystal structures with VESTA software and I noticed when generating the POSCAR output files to be read by VASP that for a simple monoatomic basis such as in elemental silicon crystals some distinct space groups produce the same exact POSCAR files (i.e. same...

what is the chemical composition of common processed paper and what does the molecule's structure look like?

My question is more general but I explain it by a simple example i.e. graphene and tight binding method. I solved energy dispersion of graphene with tight binding by the two ways: First, I took graphene as a lattice with the two basis atoms A and B. In the second way, I took graphene as a...

Dear all, I made a cad of floating structure (the frame only), figure attached below. It should be located in the water and moored, so it can't go anywhere. The CFD simulation was done. So I have fluid force on the structure. Now I want to do mechanical analysis of the structure by apply the...

So I have two sets, call it ##A## and ##B##. I also have a function ##f:A\rightarrow B##. By themselves, it does not matter (or at the very least make sense) to think of ##A## and ##B## as, say, groups (I'm not really thinking exclusively about groups, just as an example). For that matter, it...

I've written the following program for drawing the band structure Silicene nanoribbons, but in a zero energy building is a straight line. Can help me to fixed problem. % tight binding calculations for zgnr clear; clc; close all; NU=14; % Number of atoms in unit cell Nbnd=4*NU; % number of...

Homework Statement Homework EquationsThe Attempt at a Solution I am guessing P is a noble gas and Q is in group I. Therefore A, B, C and E can be canceled out. S is a transition metal. It is a metal lattice structure. But I guess it could be described as a giant structure, so would you say D...

I wants to plot band structure silicene with siesta software so that the K range is 0 to 1 but can not draw a graph in this rang. Can help me to fix the problem.

I want to plot band structure silicene in the following path: Γ→M→K→Γ Do the following equation for the above path is correct: close all clear all clc aa=2.28; a=3.86; a1=(a/2)*[sqrt(3),-1,0]; a2=(a/2)*[sqrt(3),1,0]; b1y=-(2*pi)/a; b1x=(2*pi)/(sqrt(3)*a); b2x=b1x; b2y=-b1y; %K-point pKx =...

The standard approach to explaining band structure is to assume that the electrons in a solid move in a potential from the ions, which is periodic leading to Blochs Theorem and the formation of band structure. But I am a bit confused at this point. Is the approach only valid for the valence...

Hi I recently skimmed through a book called the Structure of Theory. It's a book about what kinds of theories exist. I would like to learn more about this. What books and websites can you guys recommend? I would prefer a resource with specific examples of what kinds of theories exist in...

If like charges repel each other, what keeps the protons clustered in the nucleus of the atom from separating ? and why wouldn't the electrons with a negative charge pull them out from the nucleus ?

Hey guys, I was revising using some past papers for my structural mechanic module when I realized that I don't know how to do this problem: https://physicsforums-bernhardtmediall.netdna-ssl.com/data/attachments/83/83930-3dbc2a331721a2497ccdff8c950df951.jpg If it was for the deflection of node...

Can someone describe for me the dipole pattern that was detected related to the fine structure constant? This thread talks about that pattern some. What I am trying to understand is how that dipole is oriented relative to the observer on Earth? Are we talking about a toroidal shape with a...

I'm looking for the theoretical calculation of the hyperfine structure transition frequency of Ca-133 which is used in atomic clocks to define the second according to SI-Units. Google, Google... there is a lot about the hyperfine Hamiltonian of hydrogen, but couldn't find none about that of...

Why does glucose on prolonged heating with HI give n-hexane? What mechanism/reaction type is this? All I knew till now was that alcohols would give halogen substituted products with hydrogen halides.

Homework Statement How many covalent bonds should be there to make a molecule have a giant molecular structure? Homework EquationsThe Attempt at a Solution

Dear Forum, I know that in a solid molecules have a more compact organization. Are molecules arranged in a periodic structure, i.e. a crystal, in all solids? Do all solid have a crystalline organized structure? Polymers exhibit crystal organization of the same type only over small finite...

Hi. With regard to the Fine Structure Constant, I have been trying to figure out the practical applications of the formula in nature but have had difficulty trying to discern what the 137 denominator in the equation represents. ie, it is 1 137th of what? Or, 137 whats? Is there a practical...

What determines the crystal structure taken by metals? For example Sr has FCC and Ba BCC. The packing fraction is greater for FCC. However, due apparently to coordination number and number of "next nearest" neighbors, BCC is favored in the case of Barium despite its lower packing fraction...

I am currently taking graduate course in GR following Carroll and Wald and we just started covering causal structure. In all my years studying physics this has been the first time something made me stop and go "I would love to spend a decade on this". To me it's a perfect blend of well posed...

Please could someone explain to me what is meant by the follow sentence: "Intrinsic oxygen vacancies in the TiO2 structure might also play important roles as nucleation sites for cavitation." I understand the nucleation bit but what are "oxygen vacancies in the structure"? Any help would be...

Hi, My father has been dedicating a lot of his time to making our soon-to-be home as "rewarding" (I guess) and as nice as possible for when its done. The new side project would be this. It is supposed to be some rain-proof place for a bench/table outside. There are going to be three (more or...

What do we mean by break points in band structure ? and what that sentence means : "if the band index were chosen in such a way that the energies are indexed in ascending order for any k then break points would appear in the εnk vs. k plot (with n fixed) wherever two lines intersect." ...

What are the reasons behind the different microstructures of steel at different temperatures? I don't understand why steel at high temperatures (austenite phase) would favor an FCC crystal structure while steel at lower temperature (ferrite) would favor a BCC crystal structure.

My question is that can we use properties of quantum mechanics and thermodynamics to alter size of a non biological object such that properties like its density,optical activity, conductance etc remains same... For instance we know that cooling down a substance considerably reduces its size and...

This i know sounds like a really odd question, but thinking along the Lines that i am.. i guess it has a sense of validity. Could it be Possible, that Planets exist with Dual cores that internally orbit inside a Planet.. or partially joined. Thinking along the lines of Cell structure and how...

Hi. What are superconductor ions? Are they naturally occurring ions inside the lattice structure of a superconductor when it's manufactured or are they ions introduced artificially to a superconductor's lattice ? And do the ions have spin?

What about the structure of glass allows light to pass through, lose 10% of its energy then keep on going when all other object seem to absorb light. what makes clear objects structures so special. When the lights goes through the (regular) glass and loses energy is it losing energy in the form...

Does atom really looks and behaves like as that explained in quantum mechanical model? Or is it just a Mathematical Tool to express the observations? Is it like that that scientist were unable to find any clue about real atomic structure and just created a mathematical tools following the...

I want to write a octave code(It can be another language I want to know how should I think to write a such a code ) to obtain graphene structure like in the figure. This code should give me a graphene sheet which in size I want when I enter the position of the atoms in the lattice.I think that...

Homework Statement A uniform curved beam ABC of radius R is fixed at C and is free at end A, and carries a vertical load W at B, as shown in Fig. 3.2. Considering only bending action of W, derive expressions for the vertical and horizontal displacements as well as the rotation at end A in terms...

I need help to visualize the geometry involved here, How can I visualize the last paragraph? Why is the surface of fixed r now an ellipsoid? Also for r = 0, it is already a disk? I've tried searching for the geometry of these but I can't find any image of the geometry that I can just stare...

Assume the following set of instructions: 1. i = 0 2. if i < n, goto line 6 3. if A [ i ] = = x, goto line 7 4. i++ 5. goto line 2 6. return false 7. return true Assume that line i take Ci time, where Ci is a constant. The worst case total time of running this block of code can be calculated...

Homework Statement Homework Equations N/a The Attempt at a Solution Hi all, For part a) I simply discussed the fact that the contributions to the fine structure arise from the Darwin term, relativistic corrections to the kinetic energy, and the spin-orbital coupling with a bit of detail...

Hi, is there any software that I can use for drawing a crystal structure from atoms coordinates ?

I obtained the black hole solution whose the metric function f(r) and scalar function ##\varphi(r)## are ; ##f(r)=\frac{1}{4}+\left(\frac{Z^{2}}{2r^{2}}\right)^{2}-\frac{1}{3}\Lambda r^{2}## ##\varphi(r)=\pm\left(\frac{1}{\sqrt{2}l}\right)r## where ##Z##, ##\Lambda## and ##l## are just...

I was doing more reading in John Lee's "Introduction to smooth manifolds" and he mentioned that for every n \in \mathbb{N} such that n \neq 4 , the smooth structure that can be imposed on \mathbb{R}^n is unique up to diffeomorphism, but for \mathbb{R}^4 , there are uncountably many smooth...

I saw this antenna matrix on the north coast of California this week on vacation (a couple miles north of Half Moon Bay). It's located about 1/4 mile from the beach on Highway 1. There is a powerline running past it, but it looks to just be getting much of its power from a trickle charge from...

Homework Statement Define a structure VEHICLE which contains producer, model and chassis number. Store the content of a structure in binary search tree such that the key for storing contains all fields of a structure (producer has the highest priority, and chassis number has the lowest). Print...

Are certain DNA (genetic) strands structurally better build for survival than others? If yes, is there a term for this? For example, is there a specific order of nucleotides that is harder to destroy than another? Or if there is a specific order/combination of nucleotides that would have...

Hi, I've been working on a problem for some time now and I can't figure out why exactly this happens, and I've been looking for some insight. The phenomenon can be seen in this video. We can see that the oil rearranges itself due to a high-voltage electric field. Thinking about this, my...

hi guys i've really been struggling with this question but I still can't get any glimpse of idea on how to solve the problem, so the conditions are given in the table and what the question is asking for is the axial force acting in each members of the structure. ah, almost forgot to tell you...

Hello, I'm Harry. I'm new here, hope not breaking any posting rules in any ways :) I have a question and would like to ask for some suggestions and information. The question is about general relativity or gravity and structure of the Universe in general; I know there are definitely quite a...

I am wondering if there is any consensus on the structure terminology of the brain. 1 - I've heard that the brain has the reptilian, mammalian(limbic) and neocortex parts that overall perform specific functions and evolved in that order. - On that note, would reptiles have had any really...

So I have to do this question and I attempted this. Can anyone go over this and see if I did it correctly. Another student from my class told me I had to use the torque in order to calculate Fab but I don't see how I would do that.

Homework Statement Book says "Substances with a simple molecular structure do not conduct electricity. This is because they do not have any free electrons or an overall electric charge". Homework EquationsThe Attempt at a Solution I think the statement is a generalization because water is a...

I often encounter situations in my professional development like if ( condition1 ) { // do this } if ( condition2 ) { // do that } if ( !condition1 && !condition2 ) { // do something else } and I handle it in exactly that manner. (Note: this is not an if-elseif-else situation...

I want to do an experiment where I follow the particle in all trajectory until it hits the wall of the box, then I want to draw out this box's structure based on the particle collision. One thing would be that the particle does not need to go in all trajectory, but I would like to know how to...

Consider the Dirac equation for bounded electron in hydrogen atom. I am trying to get a clear physical explanation for all mathematical terms that appear in the Hamiltonian and energy spectrum. Kinetic and Coulombic potential and rest energies are the first terms and easy to identify. Then we...