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16:48, 26 February 2025 Csheldon talk contribs uploaded File:Chemical shielding.png (The external magnetic field B_ext induces currents in the electrons in atoms. These currents in turn induce an opposing magnetic field B_in, reducing the magnetic field at the position of the nucleus, effectively shielding the nucleus from B_ext.)
16:34, 26 February 2025 Pmelo talk contribs created page File:EELS bulk Si BSE TDHF Q2 result.png (BSE and TDHF EELS results for bulk Si at Q=0.5 0.0 0.0 for the EELS HOWTO page)
16:34, 26 February 2025 Pmelo talk contribs uploaded File:EELS bulk Si BSE TDHF Q2 result.png (BSE and TDHF EELS results for bulk Si at Q=0.5 0.0 0.0 for the EELS HOWTO page)
15:05, 26 February 2025 Csheldon talk contribs uploaded a new version of File:Quadrupolar efg.png (Removed non-spherical nucleus (too large and unclear) and enlarged the quadrupole)
14:59, 26 February 2025 Csheldon talk contribs created page File:Quadrupolar efg.png (Quadrupolar electric field of nucleus coupling to electric field gradient in MAPbI3)
14:59, 26 February 2025 Csheldon talk contribs uploaded File:Quadrupolar efg.png (Quadrupolar electric field of nucleus coupling to electric field gradient in MAPbI3)
14:22, 26 February 2025 Csheldon talk contribs uploaded a new version of File:Hyperfine coupling.png
14:19, 26 February 2025 Csheldon talk contribs created page File:Hyperfine coupling.png
14:19, 26 February 2025 Csheldon talk contribs uploaded File:Hyperfine coupling.png
11:36, 26 February 2025 Mani talk contribs created page Electron-phonon accumulators (Create page)
11:15, 26 February 2025 Jona talk contribs created page Construction:Effective potential fitting methods for phonons (Created page with "== Effective potential fitting methods for phonons == To fit the 2-body and 3-body force constant matrices molecular dynamics simulations are used to sample the effective potential energy surface for a given temperatures, volume and particle number. The molecular dynamics simulations should be conducted in the NVE ensemble, which can be set up using the following example INCAR-file. === INCAR === #INCAR molecular-dynamics tags NVE ensemble IBRION = 0...")
10:57, 26 February 2025 Csheldon talk contribs created page File:Spin energy split new colours.png (Illustration showing how the energy difference between the spin up and down electrons changes with increasing magnetic field strength. This results in a slight difference in population between the up and down states, the lower energy one being more populated.)
10:57, 26 February 2025 Csheldon talk contribs uploaded File:Spin energy split new colours.png (Illustration showing how the energy difference between the spin up and down electrons changes with increasing magnetic field strength. This results in a slight difference in population between the up and down states, the lower energy one being more populated.)
10:07, 26 February 2025 Jona talk contribs created page Construction:Finite temperature phonon renormalization with velocity correlation functions (Created page with "== Finite temperature phonon renormalization with velocity correlation functions == For a finite temperature phonon renormalization finite temperature molecular dynamics trajectories of the considered system are needed. The harmonic phonon eigenvectors are needed because the velocities obtained from the molecular dynamics run have to be projected on these. The molecular dynamics trajectories have to be done in the NVE ensemble which can be set up by the following ex...")
09:05, 26 February 2025 Csheldon talk contribs created page Construction:Hyperfine coupling calculations (Created page with "==Hyperfine coupling== The hyperfine coupling constants are calculated using {{TAG|LHYPERFINE}}, i.e. the hyperfine splitting {{Cite|szasz:prb:2013}}. Specifically, the coupling between the nuclear magnetic dipole moment and the magnetic field generated by the electrons (or nuclear spin-electron spin coupling) is referred to. For the interaction between the nuclear quadrupole moment and the electric field gradient, see {{TAG|LEFG}} and the description in insert link ba...")
15:22, 25 February 2025 Wolloch talk contribs created page Construction:Setting up a DFT calculation (Created page with "Setting up an electronic minimization calculation using density-functional theory requires a few steps. The input files must be created or copied into the execution folder. This includes making a few choices for the '''k''' point sampling and electronic smearing, minimization algorithm, and [[:Category:Exchange-correlation functionals|exchange-correlation functionals]...")
12:42, 25 February 2025 Jona talk contribs created page Construction:Category:Phonons (Created page with "Phonons are the collective excitation of nuclei in an extended periodic system. Here we will present a short summary with the complete derivation presented on the theory page. Let us start by making the Taylor expansion of the total energy <math>E </math> in terms of the ionic displacement <math> u_{I\alpha} = R_{I\alpha} - R^0_{I\alpha} </math> around the equilibrium positions of the nuclei <math>R^0_{I\alpha}</math> :<math> E(\{\mathbf{R}\})= E(...")
12:07, 25 February 2025 Jona talk contribs moved page Construction:Constraints to Construction:Geometric constraints
11:46, 25 February 2025 Schlipf talk contribs created page Construction:Integrating over all orbitals (Created page with "In this section we discuss partial occupancies. A must for all readers. First there is the question why to use partial occupancies at all. The answer is: partial occupancies help to decrease the number of k-points necessary to calculate an accurate band-structure energy. This answer might be strange at first sight. What we want to calculate is, the integral over the filled parts of the bands <math> \sum_n \frac{1}{\Omega_{\mathrm{BZ}}} \int_{\Omega_{\mathrm{BZ}}} \e...")
09:25, 25 February 2025 Ftran talk contribs created page Category:Semilocal functionals (Created page with "'''Meta-GGAs''' are a family of exchange-correlation functionals that, in addition to the electron density <math>n</math> and the gradient <math>\nabla n</math>, depend also on * the kinetic-energy density <math>\tau</math>, and/or * the Laplacian of the electron density <math>\nabla^{2}n</math>. Thus, the exchange-correlation energy can be written as :<math> E_{\mathrm{xc}}^{\mathrm{MGGA}}=\int\epsilon_{\mathrm{xc}}^{\mathrm{MGGA}}(n,\nabla n,\nabla^{2}n,\tau)d^{3...")
08:53, 25 February 2025 Ftran talk contribs created page Construction:Category:Exchange-correlation functionals (Created page with "In the Kohn-Sham (KS) formulation of density-functional theory (DFT){{cite|hohenberg:pr:1964}}{{cite|kohn:pr:1965}}, the total energy is given by :<math> E_{\rm tot}^{\rm KS-DFT} = -\frac{1}{2}\sum_{i}\int\psi_{i}^{*}({\bf r})\nabla^{2}\psi_{i}({\bf r})d^{3}r - \sum_{A}\int\frac{Z_{A}}{\left\vert{\bf r}-{\bf R}_{A}\right\vert}n({\bf r})d^{3}r + \frac{1}{2}\int\int\frac{n({\bf r})n({\bf r'})}{\left\vert{\bf r}-{\bf r'}\right\vert}d^{3}rd^{3}r' + E_{\rm xc} + \frac{1}{2}\s...")
07:37, 25 February 2025 Jona talk contribs created page Construction:Constraints (Created page with "== Geometric constraints == === Define two constraints === The following constrains the bond lengths between atoms 1 and 5, and between atoms 1 and 6. R 1 5 0 R 1 6 0 === Use complex coordinates === Consider, for instance, the {{TAG|ICONST}} file with the following lines: R 1 6 0 R 1 5 0 S 1 -1 0 The first two lines define two primitive coordinates - bonds between the atoms <math>1</math> and <math>6</math>, and between the atoms <math>1</math> and <math>5</ma...")
16:13, 24 February 2025 Schlipf talk contribs uploaded a new version of File:Dos-gauss-tetra.png
16:07, 24 February 2025 Schlipf talk contribs created page File:Dos-gauss-tetra.png
16:07, 24 February 2025 Schlipf talk contribs uploaded File:Dos-gauss-tetra.png
15:42, 24 February 2025 Csheldon talk contribs moved page Constrained molecuar dynamics calculations to Constrained molecular dynamics calculations (Misspelled title)
15:33, 24 February 2025 Ftran talk contribs created page Construction:Category:Van der Waals functionals (Created page with "The semilocal and hybrid exchange-correlation functionals do not include the London dispersion forces. Therefore, they can not be applied reliably on systems where the London dispersion forces play an important role. To account more properly for the London dispersion forces in DFT, a correlation dispersion term can be added to the semilocal or hybrid functional. This leads to the so-called '''van der Waals functionals''': :<math> E_{\text{xc}} = E_{\text{xc}}^{\text{SL/h...")
14:52, 24 February 2025 Csheldon talk contribs created page Construction:NMR (Created page with "Many nuclei have an inherent, non-zero spin '''I''' and therefore a magnetic dipole moment '''μ''', conventionally along the z-axis: :<math> \mu_z = \gamma \textbf{I}_z </math> In the absence of a magnetic field, these are degenerate states. When an external magnetic field '''B'''<sub>ext</sub> is applied, the energy difference between two states is given by the following equation: :<math> \Delta E = \gamma \hbar \textbf{B}_{ext} </math> Conventionally, the z-axis...")
14:25, 24 February 2025 Schlipf talk contribs created page File:Smearing.png
14:25, 24 February 2025 Schlipf talk contribs uploaded File:Smearing.png
10:56, 24 February 2025 Schlipf talk contribs created page Construction:Smearing technique (Created page with " == How to set ISMEAR == For the calculation of the ''total energy'' in bulk materials, we recommend the tetrahedron method with Blöchl corrections ({{TAG|ISMEAR}}=-5). This method also gives a good account of the electronic density of states (DOS). The only drawback is that the method is not variational with respect to the partial occupancies. Therefore the calculated forces and the stress tensor can be wrong by up to 5 to 10% for metals...")
10:39, 24 February 2025 Schlipf talk contribs created page Smearing technique (Created page with " == How to set ISMEAR == For the calculation of the ''total energy'' in bulk materials, we recommend the tetrahedron method with Blöchl corrections ({{TAG|ISMEAR}}=-5). This method also gives a good account of the electronic density of states (DOS). The only drawback is that the method is not variational with respect to the partial occupancies. Therefore the calculated forces and the stress tensor can be wrong by up to 5 to 10% for metals...")
08:46, 24 February 2025 Ftran talk contribs created page Construction:IVDW (Created page with "{{TAGDEF|IVDW|0 {{!}} 1 {{!}} 10 {{!}} 11 {{!}} 12 {{!}} 13 {{!}} 14 {{!}} 2 {{!}} 20 {{!}} 21 {{!}} 202 {{!}} 263 {{!}} 3 {{!}} 4|0 (no correction)}} Description: {{TAG|IVDW}} specifies a vdW (dispersion) correction. ---- For fundamental reasons, the semilocal and hybrid exchange-correlation functionals are unable to describe properly vdW interactions resulting from dynamical correlations between fluctuating charge distributions (called London dispersion forces). An ap...")
16:19, 21 February 2025 Tal talk contribs moved page Construction:Best practices for Bethe-Salpeter calculations to Best practices for Bethe-Salpeter calculations
16:18, 21 February 2025 Tal talk contribs created page Construction:Best practices for Bethe-Salpeter calculations (Created page with "== Optimizing performance == Due to the steep scaling of the BSE method with the system size, it is important to optimize the parameters of the calculation. Here we provide recommendations that can significantly speed up the BSE calculations in VASP. Below we consider two limiting cases: small cells and large cells. === Small cells === We consider that small cells are the cells where the number of atoms doesn't exceed ''eight''. For such cells, it is typical that a larg...")
10:59, 21 February 2025 Tal talk contribs created page BSE theory (Redirected page to Bethe-Salpeter-equations) Tag: New redirect
10:54, 21 February 2025 Tal talk contribs uploaded a new version of File:Bse graph.png
10:47, 21 February 2025 Tal talk contribs created page File:Bse graph.png
10:47, 21 February 2025 Tal talk contribs uploaded File:Bse graph.png
15:38, 20 February 2025 Tal talk contribs created page Bethe-Salpeter equation (Created page with "== Bethe-Salpeter equation == The Bethe-Salpeter equation (BSE) was first derived and applied in the context of particle physics and QED in 1951 {{cite|salpeter:pr:1951}}. The first application of BSE in solids was done by Hanke {{cite|hanke:prl:1979}}, who calculated the absorption spectrum of bulk silicon in qualitative agreement with experiment. Since then numerous works have shown successful applications of BSE for describing optical properties of materials and BSE h...")
13:58, 19 February 2025 Tal talk contribs created page File:Fch xch.png
13:58, 19 February 2025 Tal talk contribs uploaded File:Fch xch.png
12:58, 18 February 2025 Kaltakm talk contribs created page Construction:MSDGW NP (Created page with "{{TAGDEF|MSDGW_NP|[integer]|2*max(NELECT/2+NIONS/2,NELECT*0.6)}} Description: Number of protected bands in mixed stochastic-deterministic compression algorithm.{{cite|altman:prl:2024}} ---- {{TAG|MSDGW_NP}} determines how many bands are protected by the mixed stochastic-deterministic compression of unoccupied bands. Bands beyond {{TAG|MSDGW_NP}} are compressed. This tag is set in combination with {{TAG|MSDGW_F}}, the constant energy ratio <math>F</math> of the compressi...")
12:36, 18 February 2025 Kaltakm talk contribs created page Construction:MSDGW NXI (Created page with "{{TAGDEF|MSDGW_NXI|[integer]|2}} Description: Number of pseudo orbitals per compressed energy of mixed stochastic-deterministic compression algorithm.{{cite|altman:prl:2024}} ---- {{TAG|MSDGW_NXI}} sets the number of stochastic orbitals per energy in the unprotected space beyond band {{TAG|MSDGW_NP}}. This tag is set in combination with {{TAG|MSDGW_F}}, the constant energy ratio <math>F</math> of the compression algorithm. If a positive value of {{TAG|MSDGW_F}} is found...")
11:26, 18 February 2025 Kaltakm talk contribs created page Construction:MSDGW F (Created page with "{{TAGDEF|MSDGW_F|[real]|-1}} Description: A positive value of {{TAG|MSDGW_F}} triggers the mixed stochastic-deterministic compression algorithm of Altman and co-workers.{{cite|altman:prl:2024}} ---- {{TAG|MSDGW_F}} is the constant energy ratio <math>F</math> of the compression algorithm. If set to a positive value, energies beyond the protected space defined by {{TAG|MSDGW_NP}} are subdivided into energy bins of width <math>\Delta E_i</math> and replaced by other energi...")
09:20, 18 February 2025 Karsai talk contribs moved page SCH calculations to Supercell core-hole calculations
09:15, 18 February 2025 Karsai talk contribs moved page XAS theory to Supercell core-hole theory
11:16, 17 February 2025 Hampel talk contribs created page Vaspgamma.h5 (Created page with "The {{FILE|vaspgamma.h5}} file is an input file used when {{TAG|ICHARG}}=5 is set. It is read by VASP during an electronic minimization to incorporate additional occupation changes per k-point and orbital before calculating a new charge density. The file is only read when VASP is compiled with HDF5 support enabled and the {{FILE|GAMMA}} is not present. {{Available|6.5.0}} ---- {{NB|mind|When reading and writing from and to hdf5 archive...")
10:14, 17 February 2025 Pmelo talk contribs created page File:EELS bulk Si DFT result.png (Bulk Si EEL spectrum from DFT for EELS HOWTO page)
10:14, 17 February 2025 Pmelo talk contribs uploaded File:EELS bulk Si DFT result.png (Bulk Si EEL spectrum from DFT for EELS HOWTO page)