mirror of https://github.com/abinit/abinit.git
56 lines
2.1 KiB
Markdown
56 lines
2.1 KiB
Markdown
---
|
|
description: How to perform a DFT+U calculation
|
|
authors: BAmadon
|
|
---
|
|
<!--- This is the source file for this topics. Can be edited. -->
|
|
|
|
This page gives hints on how to perform a DFT+U calculation with the ABINIT package.
|
|
|
|
## Introduction
|
|
|
|
This feature is available only in PAW. The DFT+U framework is described in
|
|
[[cite:Anisimov1991]] and [[cite:Liechtenstein1995]]. In ABINIT, the DFT+U
|
|
approximation is implemented inside the PAW atomic spheres only. Two choices
|
|
of double counting are provided: the Full Localized limit and the Around Mean
|
|
Field approximation. Our implementation is described in [[cite:Amadon2008a]].
|
|
It follows the main lines of [[cite:Bengone2000]]. See also
|
|
[[cite:Czyzyk1994]]. Forces and stress are implemented. For details on
|
|
keywords ([[lpawu]], [[upawu]], [[jpawu]], [[usedmatpu]], [[dmatpuopt]],
|
|
[[dmatudiag]]) see keyword [[usepawu]] in input variables.
|
|
|
|
In both the output and log files, we can find:
|
|
|
|
- The DFT+U contribution of energy which is contained inside the PAW
|
|
Spherical terms in the output file.
|
|
|
|
- The Decomposition of the DFT+U energy is given (Interaction energy, Double
|
|
counting term, and sum of the two) in the log file.
|
|
|
|
- The orbital density matrix ($n_{m,m'}^{\sigma}$), also called occupation
|
|
matrix (corresponding to Eq.(9) of [[cite:Bengone2000]] and Eq.(1) of
|
|
[[cite:Liechtenstein1995]], see also [[cite:Amadon2008a]] and variable
|
|
[[dmatpuopt]]) is also given for each atom in the basis of real spherical
|
|
harmonics. It is given at each SCF step in the log file: one can thus check
|
|
the convergency of the calculation.
|
|
|
|
Consistency between total energy and forces in DFT+U have been checked.
|
|
|
|
The implementation of DFT+U in ABINIT allows also to impose a starting density
|
|
matrix in order to compare the energy of various electronic configuration (see
|
|
keywords [[usedmatpu]] and [[dmatpawu]]).
|
|
|
|
|
|
|
|
## Related Input Variables
|
|
|
|
{{ related_variables }}
|
|
|
|
## Selected Input Files
|
|
|
|
{{ selected_input_files }}
|
|
|
|
## Tutorials
|
|
|
|
* [[tutorial:dftu|The tutorial on DFT+U]] shows how to perform a DFT+U calculation using ABINIT, and will lead to compute the projected DOS of NiO. Prerequisite: PAW1.
|
|
|