Difference between revisions of "Non self-consistent calculations: Band structures and Density Of States"
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(Created page with " Prev: LabQSM#Lecture 1: Basic DFT calculations and Convergences Next: [[]] ==Non self-consistent calculations: Intro== left |thumb Once the ch...") |
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Prev: [[LabQSM#Lecture 1: Basic DFT calculations and Convergences]] | Prev: [[LabQSM#Lecture 1: Basic DFT calculations and Convergences]] | ||
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==Non self-consistent calculations: Intro== | ==Non self-consistent calculations: Intro== | ||
| − | [[File: | + | [[File:si band structure.png|left |thumb | Silicon band structure. Originals from [https://www.tf.uni-kiel.de/matwis/amat/td_kin_ii/index.html Thermodynamics and |
| + | Kinetics II, Dr. J. Carstensen, Univ. Kiel] ]] | ||
Once the charge density has been obtained in a scf run, more calculations can be performed at fixed density (non-scf). | Once the charge density has been obtained in a scf run, more calculations can be performed at fixed density (non-scf). | ||
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calculation="bands" # kpts along lines | calculation="bands" # kpts along lines | ||
| − | K-points (and number of bands if relevant) need to be specified | + | K-points (and number of bands if relevant) need to be specified. |
Revision as of 07:37, 16 December 2020
Prev: LabQSM#Lecture 1: Basic DFT calculations and Convergences
Non self-consistent calculations: Intro
Silicon band structure. Originals from [https://www.tf.uni-kiel.de/matwis/amat/td_kin_ii/index.html Thermodynamics and Kinetics II, Dr. J. Carstensen, Univ. Kiel]
Once the charge density has been obtained in a scf run, more calculations can be performed at fixed density (non-scf). Among these:
- calculations of Kohn-Sham energies and orbitals on any given set of k-points (i.e. without specific aim of represent a reasonable sampling of the BZ);
- calculations as above, also increasing the number of computed (= diagonalized) bands (incl the calculation of empty Kohn-Sham states);
- Importantly, nscf calculations are typically done to plot KS bands or compute the DOS,
- but also as a preliminary step to other calculations (e.g. uniform k-point samplings and large amounts of empty states are using in GW and other many-body perturbation theory algorithms implemented with sum-over-states techniques)
In the Quantum ESPRESSO input file one has to set:
calculation="nscf" # kpts sampling BZ
or
calculation="bands" # kpts along lines
K-points (and number of bands if relevant) need to be specified.