What is Dft: Definition and 120 Discussions

The Department for Transport (DfT) is the government department responsible for the English transport network and a limited number of transport matters in Scotland, Wales and Northern Ireland that have not been devolved. The department is run by the Secretary of State for Transport, currently (since 24 July 2019) Grant Shapps.

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  1. J

    DFT: What is the physical meaning of the symmetry about the nyquist frequency?

    When I take the fft of a set of data and plot it, there is a reflection around the nyquist. Everybody knows this, but I would like to know what the physical meaning of the second half (the reflected half) is. The real component is the same as the first half, and the imaginary component has...
  2. M

    Semi-Infinite DFT Software

    Hello, Does anybody know commercial codes in which you can implement semi-infinite boundary conditions for surface calculations. I know for modeling metallic adhesion semi-infinite BC's have been used in the past along with a Jellium potential approximation. Unfortunately, I've been searching...
  3. W

    Density Matrix in that DFT bible book

    -- i know there were threads about reduced density matrix in this forum, but I am reading "Density-functional theory of atoms and molecules" by Parr R., Yang W., their notation is quite confusing to me... their notation is the same as shown in this page...
  4. P

    How to calculate the basis function energy from DFT programs?

    Dear all: I need to calculate the density of states of electrons from metallic clusters. I ran a DFT program and output the mulliken population analysis datas, such as the following: (I show only part of the data) ATOM # 1 ORBITAL ALPHA OCCUPATION 5s...
  5. K

    Understanding DFT & Graphene: Schrodinger vs Dirac

    Hello all, I have read a few papers lately that have used DFT based techniques to investigate metallic adatom adsorption on top of graphene (see for instance PRB 77, 235430 2008). I was under the impression that electrons in graphene are described by the Dirac equation and not the...
  6. hxtasy

    Sliding DFT discrete Fourier transform

    "Sliding DFT" discrete Fourier transform... I was wondering if any of you had had experience with the sliding DFT algorithm. It is somewhat similar to the Goertzel algorithm. I am having some trouble understanding the mathematics of the algorithm, and I also cannot seem to identify a useful...
  7. T

    DFT vs Van de Waals: Explaining the Difference

    Hi everybody, Can you tell me, in general, why Density Functional Theory does not describe the Van de Waals interaction? Many thanks,
  8. R

    How Do I Calculate Bulk Modulus from DFT Data for Solid Carbon Dioxide?

    Homework Statement I have been asked to calculate the bulk modulus for a carbon dioxide solid from data I have calculated. I have made a quick plot of unit cell size vs pressure (sorry for no labels, unit cell is Y axis as square angstroms, and pressure is in GPa), which looks ok...
  9. D

    Optimizing DFT Homework: Split-Radix & Cooley-Tukey

    Homework Statement Given a discrete Fourier transform, create a fast Fourier transform. Homework Equations The DFT: X_k = \sum_{n=0}^{N-1} x_n e^{-\frac{2 \pi i}{N} k n} \quad \quad k = 0, \dots, N-1 The Attempt at a Solution I've heard about split-radix and Cooley-Tukey, but I'm...
  10. H

    Converging your DFT calculations

    any CASTEP users or DFT planewave-pseudopotential method users out there? how do I ensure that the basis set is adequate? I'm performing calculations with a rather large unit cell ( orthorhombic, 8 atoms/cell) of a compound AB. Can I justify my choice of energy-cutoff by testing...
  11. H

    Enthelpy of Formation From DFT

    Has anyone had experience with calculating the enthalpy of formation from DFT? I have had a few calculations with the planewave-pseudopotential method. What puzzles me is that in one case the agreement with experimental values is excellent, while another case was about 30% more stable...
  12. N

    Exploring Tight-Binding & DFT: Justifying Non-Interacting Electrons

    What is the justification behind tight-binding, nearly free electron drude model, to assume electrons as non-interacting? Because it is clearly not the case when considering coloumbic interactions, why can these models do this? Coloumbic interactions are strong so I wouldn't consider them to be...
  13. G

    Understanding the Exchange-Correlation Term in Density Functional Theory

    Hi, i can't understan clearly the Exchange-correlation term that appears in the develop of DFT. The only thing i know is that the first comes from the pauli exclusion principle, and the second from the quantum part of the coulomb interaction between electrons. Am i right?? but i wan't to go...
  14. L

    DFT - zero padding avoids aliasing?

    hey guys - i can't seem to find find this statement anywhere - but it makes sense to me - could someone please verify. When you find the DFT of a signal say: x[0]=2, x[1]=4, x[2]=6, x[3]=8 - you will get four discrete points in frequency (per period) now if you zero pad the time signal such...
  15. L

    DFT - can't evaluate components in -negative time

    DFT - can't evaluate components in -negative time! hey guys - if you look at the definition/equation of discrete Fourier transform, you will see that we can only evaluat values from n=0 to N (see http://en.wikipedia.org/wiki/Discrete_Fourier_transform, to view the equation)...but what have we...
  16. F

    Simple DFT Software for Tutorials - Windows Platform

    "Simple" DFT software Hi, is anybody aware of a "ligthweight" DFT software to be used as a tutorial (say for undergraduate students, etc.), so very simple to configure, use, and visualize results? Installation on a Windows platform would be the best... thanks Fabio
  17. H

    How to calcualte C-C bond energy of diamond by DFT

    Dear all: I want to calculate the C-C bond energy of diamond and the dangling bond energy on diamond surface by DFT. How can I do? Can you tell me ? Thanks a lot! H. L. Yu :confused:
  18. Q

    Admissions Chances in applying for a PhD in Physics (DFT)

    Hi All! I was wondering what are my chances in applying for a PhD in physics... I have a master's degree, I was involved in some computational stuff in Density Functional Theory, I also graduated in this field. My problem is, that I have not been some eager-beaver guy with my studies...
  19. L

    MATLAB Finding DFT and DTFT of 12-Point Sequence with MatLab

    I'm considering the 12 –point sequence x[n] which is defined as x[n] = {1, 2, 3, 4, 5, 6, 6, 5, 4, 3, 2, 1}. I'd like to use Matlab to find the DFT (X[k] of x[n]) and DTFT (X(e^jw) of x[n]). I realize that the DFT is sampled version of DTFT, and I want to show this graphically using...
  20. S

    Looking for Tensor and DFT e-print

    Someone helps me ! I'm looking for where I can download free e-print about Tensor Calculus and Density Functional Theory . I want to teach myself. Thank you very much .
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