An order N code using wavelet as basis set has been developed in the framework of an European project called BigDFT (FP6-NEST,http://www). The four participants of the project who propose this tutorial are:
- Prof. Stefan Goedecker (Basel University, Switzerland),
- Prof. Xavier Gonze (UCL, Belgium),
- Prof. Reinhold Schneider (Kiel University, Germany) and
- Dr. Thierry Deutsch (CEA-Grenoble, France).
This code called bigdft will be provided soon (v5.3) inside the package of ABINIT. It is based on wavelet functions which have some nice properties of locality in real space. Moreover, this basis set is systematic: the accuracy depends only on the grid step.
The goal of the tutorial is to demonstrate the capabilities of this new code and describe the associated mathematics and algorithms. A part of the tutorial will be also devoted to abinit as the code bigdft is complementary to a plane-wave code:
- Treatment of isolated systems (neutral or charged) or surfaces with proper boundary conditions;
- Order N method;
- Adaptivity of the mesh.
This new method can be helpful for chemists, physicists to perform the calculations of large molecules, molecules on surface or inhomogeneous systems.