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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
17:10, 12 February 2025 Tal talk contribs created page Bethe-Salpeter equation for core excitations (Created page with "VASP offers two approaches for calculating the X-ray Absorption Near Edge Structure ([https://en.wikipedia.org/wiki/X-ray_absorption_near_edge_structure XANES]). The supercell core-hole (SCH) method and the Bethe-Salpeter equation (BSE). Within the BSE approach, the two-particle polarizability <math>L(\mathbf{r}_1,\mathbf{r}_2,\mathbf{r}_3,\mathbf{r}_4,\omega)</math> is found by solving the equation ::<math>\bar{L}(\omega)=L_0(\omega)+L_0(\omega)(\bar{v}-W...")
09:53, 18 December 2024 Tal talk contribs moved page Construction:NBSEBLOCKO to NBSEBLOCKO
09:52, 18 December 2024 Tal talk contribs moved page Construction:NBSEBLOCKV to NBSEBLOCKV
09:52, 18 December 2024 Tal talk contribs moved page Construction:LANCZOSTHR to LANCZOSTHR
10:03, 11 June 2024 Tal talk contribs created page Construction:NBSEBLOCKO (Created page with "{{TAGDEF|NBSEBLOCKO|[integer]}} {{DEF|NBSEBLOCKO|-1|}} Description: {{TAG|NBSEBLOCKO}} specifies the blocking factor for the occupied states when setting up the BSE Hamiltonian. ---- By default, the construction of the BSE Hamiltonian in VASP is parallelized over k-points, such that each MPI rank can compute a pair of k-points. This way the BSE Hamiltonian setup can be parallelized up to <math>\mathrm{NKPTS*(NKPTS+1)/2}</math> MPI ranks or <math>\mathrm{NKPTS*2*(NKPTS*2...")
10:00, 11 June 2024 Tal talk contribs created page Construction:NBSEBLOCKV (Created page with "{{TAGDEF|NBSEBLOCKV|[integer]}} {{DEF|NBSEBLOCKV|-1|}} Description: {{TAG|NBSEBLOCKV}} specifies the blocking factor for the unoccupied states when setting up the BSE Hamiltonian. ---- By default, the construction of the BSE Hamiltonian in VASP is parallelized over k-points, such that each MPI rank can compute a pair of k-points. This way the BSE Hamiltonian setup can be parallelized up to <math>\mathrm{NKPTS*(NKPTS+1)/2}</math> MPI ranks or <math>\mathrm{NKPTS*2*(NKPTS...")
15:08, 10 June 2024 Tal talk contribs created page SCISSOR (Created page with "{{TAGDEF|SCISSOR|[real]}} {{DEF|SCISSOR|0|}} Description: {{TAG|SCISSOR}} specifies the shift for the scissor operator in eV. ---- Scissor operator in GW and BSE calculations shifts the conduction bands relative to the valence states{{cite|vincenzo:prb:1995}}. For example, scissor operator can be used in the BSE calculations to match the band gap to the known experimental value, thus achieving the right offset in the calculated spectrum. Notably, unlike the self-energy...")
09:24, 12 February 2024 Tal talk contribs moved page Construction:Plot exciton wavefunction to Construction:Plotting exciton wavefunction
17:48, 7 February 2024 Tal talk contribs created page TDDFT calculations (Redirected page to Bethe-Salpeter-equations calculations) Tag: New redirect
17:44, 7 February 2024 Tal talk contribs moved page Construction:Time-dependent density-functional theory calculations to Time-dependent density-functional theory calculations
16:03, 7 February 2024 Tal talk contribs created page Construction:BSEELECTRON (Created page with "{{TAGDEF|BSEELECTRON|[integer],[integer],[integer]|}} Description: {{TAG|BSEELECTRON}} sets the coordinates of the fixed electron in the exciton wavefunction calculated in BSE. The coordinates are provided in direct (fractional) coordinates. == Related tags and sections == {{TAG|BSE}}, {{TAG|BSEFATBAND}}, BSE calculations {{sc|NBSEEIG|Examples|Examples that use this tag}} ---- Category:INCAR tag Category:Many-body perturbation theoryCategory:Bethe-Salpeter...")
15:41, 7 February 2024 Tal talk contribs created page Construction:BSEHOLE (Created page with "{{TAGDEF|NBSEEIG|[integer]|1}} Description: {{TAG|NBSEEIG}} sets the number of BSE eigenvectors written to the {{FILE|BSEFATBAND}} output file. == Related tags and sections == {{TAG|BSE}}, {{TAG|BSEFATBAND}}, BSE calculations {{sc|NBSEEIG|Examples|Examples that use this tag}} ---- Category:INCAR tag Category:Many-body perturbation theory Category:Bethe-Salpeter equations")
15:10, 29 January 2024 Tal talk contribs created page Construction:Plot exciton wavefunction (Created page with "The exciton wavefunction can be written as <math>\psi_\lambda\left(r_e,r_h\right)=\sum_{vc} A_{vc}^\lambda \psi_v(r_h)\psi_c^*(r_e)</math> and depends on coordinates of a hole as well as an electron, thus two coordinates. In order to represent this function in 3D space we need to fix either the position of the electron $\psi_\lambda(r^*_e,r_h)$ or that of the hole $\psi_\lambda(r_e,r^*_h)$ File:HBN exciton.png|500px|thumb|Charge density of the first bright exciton...")
15:01, 29 January 2024 Tal talk contribs created page File:HBN exciton.png (Charge-density of the first bright exciton in hBN.)
15:01, 29 January 2024 Tal talk contribs uploaded File:HBN exciton.png (Charge-density of the first bright exciton in hBN.)
09:04, 26 October 2023 Tal talk contribs moved page Plot BSE fatband to Plot BSE fatbands
09:04, 26 October 2023 Tal talk contribs moved page Plotting the BSE fatband structure to Plot BSE fatband
11:59, 20 October 2023 Tal talk contribs moved page Construction:BSEPREC to BSEPREC
11:59, 20 October 2023 Tal talk contribs moved page Construction:IBSE to IBSE
10:41, 20 October 2023 Tal talk contribs created page Construction:IBSE (Created page with "{{TAGDEF|IBSE|[integer]}} {{DEF|IBSE| 0 | }} Description: {{TAG|IBSE}} can be used to select the algorithm for solving the Bethe-Salpeter or Casida equation. ---- The follow...")
08:50, 20 October 2023 Tal talk contribs created page Construction:BSEPREC (Created page with "{{TAGDEF|BSEPREC|Low {{!}} Medium {{!}} High {{!}} Accurate | Medium}} Description: {{TAG|BSEPREC}} determines the precision for the time-evolution calculation in BSE and T...")
14:11, 17 October 2023 Tal talk contribs moved page Construction:Time-dependent density functional theory calculations to Construction:Time-dependent density-functional theory calculations
14:10, 17 October 2023 Tal talk contribs created page Construction:Time-dependent density functional theory calculations (Created page with "VASP offers a powerful module for performing time-dependent density functional theory (TDDFT) or time-dependent Hartree-Fock (TDHF) calculations in the Casida formulation {{ci...")
16:33, 16 October 2023 Tal talk contribs moved page Construction:Plotting the BSE fatband structure to Plotting the BSE fatband structure
16:26, 16 October 2023 Tal talk contribs created page Construction:Category:Time-dependent density functional theory (Created page with "The formalism of the Bethe-Salpeter equation (BSE) allows for calculating the polarizability with the electron-hole interaction and constitutes the state of the art for calcul...")
07:19, 24 October 2022 Tal talk contribs moved page Construction:IALL IN ONE to Construction:IALL IN ONE MBPT
07:03, 24 October 2022 Tal talk contribs created page Construction:IALL IN ONE (Created page with "{{TAGDEF|IALL_IN_ONE_MBPT|0 {{!}} 1 }} {{DEF|IALL_IN_ONE_MBPT|0|}} Description: {{TAG|IALL_IN_ONE_MBPT}} enables the all-in-one MBPT calculation, i.e., {{TAG|ALGO}}= GWR, RP...")
15:59, 20 July 2022 Tal talk contribs created page File:Bsefatband.png
15:59, 20 July 2022 Tal talk contribs uploaded File:Bsefatband.png
15:49, 20 July 2022 Tal talk contribs created page File:Bsefatband.pdf
15:49, 20 July 2022 Tal talk contribs uploaded File:Bsefatband.pdf
14:42, 20 July 2022 Tal talk contribs created page Construction:Plotting the BSE fatband structure (Created page with "It can be useful to inspect which electron-hole pairs contribute the most to a particular BSE eigenvector. In VASP it is possible to write the first {{TAG|NBSEEIG}} eigenvecto...")
12:52, 8 April 2022 Tal talk contribs created page LORBITALREAL (Created page with "{{TAGDEF|LORBITALREAL|.TRUE. {{!}} .FALSE.}} {{DEF|LORBITALREAL|.FALSE.|}} Description: {{TAG|LORBITALREAL}} forces VASP to make the orbitals <math> \phi({\bf r}) </math> rea...")
14:26, 7 April 2022 Tal talk contribs created page LFXC (Created page with "{{TAGDEF|LFXC|.TRUE. {{!}} .FALSE.}} {{DEF|LFXC|.FALSE.|}} Description: {{TAG|LFXC}} enables the local exchange-correlation kernel in TD-DFT and BSE ca...")
12:08, 1 February 2022 Tal talk contribs created page WPLASMAI (Created page with "{{TAGDEF|WPLASMAI|[real]|0}} Description: {{TAG|WPLASMAI}} sets the imaginary part of plasma frequency in eV. ---- If {{TAG|WPLASMAI}}>0 the Drude term is added to the densit...") Tag: Visual edit: Switched