SIESTA (Spanish Initiative for Electronic Simulations with Thousands of Atoms) is an original method and its computer program implementation, to efficiently perform electronic structure calculations and ab initio molecular dynamics simulations of molecules and solids. SIESTA uses strictly localized basis sets and the implementation of linear-scaling algorithms. Accuracy and speed can be set in a wide range, from quick exploratory calculations to highly accurate simulations matching the quality of other approaches, such as the plane-wave and all-electron methods. SIESTA's backronym is the Spanish Initiative for Electronic Simulations with Thousands of Atoms. Since 13 May 2016, with the 4.0 version announcement, SIESTA is released under the terms of the GPL open-source license. Source packages and access to the development versions can be obtained from the DevOps platform on GitLab. The latest version Siesta-4.1.5 was released on 4 February 2021.

Features

SIESTA has these main characteristics: SIESTA routinely provides: And also (though not all options are compatible):

Strengths of SIESTA

SIESTA's main strengths are: The use of a linear combination of numerical atomic orbitals makes SIESTA a DFT code. SIESTA can produce very fast calculations with small basis sets, allowing the computation of systems with thousands of atoms. Alternatively, the use of more complete and accurate bases achieves accuracies comparable to those of standard plane wave calculations, with competitive performance.

Implemented Solutions

SIESTA is in continuous development since it was implemented in 1996. The main solutions implemented in the current version are:

Solutions under development

Post-processing tools

Several post-processing tools for SIESTA have been developed. These programs process SIESTA output or provide additional features.

Applications

Since its implementation, SIESTA has been used by researchers in geosciences, biology, and engineering (extending beyond materials physics and chemistry) and has been applied to a large variety of systems including surfaces, adsorbates, nanotubes, nanoclusters, biological molecules, amorphous semiconductors, ferroelectric films, low-dimensional metals, etc.