# Ab initio

A calculation is said to be *ab initio* (or "from first principles") if it relies on basic and established laws of nature without additional assumptions or special models
(Wikipedia).

In our group we use various *ab initio* approaches to study basic properties of different materials ranging from electron density of states up to magnetic and transport properties.

# Atomistic spin dynamics

**Atomistic spin dynamics** is a microscopic method of modelling magnetization dynamics in solid state combining first principle (*ab initio*) calculations with Landau-Lifshitz-Gilbert equation. By means of this method one assign a magnetic moment to each atom in the studied system. These magnetic moments interact via the exchange interactions, calculated using *ab initio* methods. Finally, the exchange interactions are included in the local effective magnetic fields, which govern the manetization dynamics

Atomistic spin dynamics can be used to examine magnetic properties of various materials as well as complex behaviour of magnetic moments influeced by spin transfer torque or temperature gradients studied in spintronics.

## Involved researchers

# Density functional theory

**Density functional theory** is a computational quantum mechanical modelling method used in physics, chemistry and materials science to investigate the electronic structure (principally the ground state) of many-body systems, in particular atoms, molecules, and the condensed phases (Wikipedia).

# Topological insulators

A topological insulator is a material with non-trivial topological order that behaves as an insulator in its interior but whose surface contains conducting states, meaning that electrons can only move along the surface of the material (Wikipedia).

In our group we continuously study bulk conductivity and magnetic properties of Bismuth chalcogenides (Bi_{2}Se_{3} and Bi_{2}Te_{3}) doped by magnetic atoms like Mn, Fe or Cr.

**Direct URL:**http://theory.kfkl.cz/staff/sebesta