# Features

Jx support the following features:

*J* in momentum space.

MFT is a linear response calculation and can be performed in momentum space. Therefore, MFT can compute short and long-term interactions in moment space, without multiple real space supercells calculations.

*J* coupling matrix (Orbital resolved interactions)

A useful feature of MFT is to calculate the orbitally decomposed magnetic response function.
It means that a magnetic coupling constant is extended to a matrix. If we consider **d** orbital system, for example, each magnetic atom has five magnetic orbitals and the magnetic coupling J_{12} (in between atom 1 and atom 2) is expressed by a 5X5 matrix *J*_{12}.

## Local axis redefinition for orbital resolved *J*

In practice, a difficulty in analyzing magnetic materials arises from the absence of well-defined global coordinate axis.
A typical example is the distorted oxides in which the local `x,y,z`

coordinate at one site is not the same at another. When one tries to calculate the orbital-dependent magnetic coupling, this ambiguity can cause annoying problems. With this motivation, *Jx* provides functionality for the user to re-define the local coordinates.

## Support mulitple Tight-binding Hamiltonian

Basically, any tight-binding style Hamiltonian could be utilized for Jx. Currently we support following interfaces:

- Full DFT Hamiltonian from OpenMX
- Wannier
- Openmx Wannier.
- Wannier90.
- Adding custom Hamilton format interfaces are also possible.

- Full DFT/QSGW Hamiltonian from EcalJ