In the step 3, real-space charge/spin current density is calculated optionally. The parameter for this calculation is as follows:

NEGF.tran.CurrentDensity on # default on

`NEGF.tran.CurrentDensity`

If

`NEGF.tran.CurrentDensity`

is set to`on`

, the real-space current density is calculated.

In the calculation of the current density, `openmx`

makes the following standard output:

Start Calculation of the currentdensity Spin #0 Sum of current in real space [a.u.] Left(ideal) : -9.10585e-06 Right(ideal): -9.10583e-06 Left(truncated ): -8.66971e-06 Right(truncated): -8.69926e-06 Spin #1 Sum of current in real space [a.u.] Left(ideal) : -4.54540e-08 Right(ideal): -4.54544e-08 Left(truncated ): -4.19469e-08 Right(truncated): -4.27460e-08 Output: Currentdensity Charge-current density along a-axis: ./negf-8zgnr-0.3.curden1.cube Spin-current density along a-axis: ./negf-8zgnr-0.3.scurden1.cube Charge-current density: ./negf-8zgnr-0.3.curden.xsf Spin-current density: ./negf-8zgnr-0.3.scurden.xsf Voronoi Charge-current density: ./negf-8zgnr-0.3.curden_atom.xsf Voronoi Spin-current density: ./negf-8zgnr-0.3.scurden_atom.xsf

In this case, 6 files,
`negf-8zgnr-0.3.curden.xsf`

, `negf-8zgnr-0.3.scurden.xsf`

,
`negf-8zgnr-0.3.curden1.cube`

, `negf-8zgnr-0.3.scurden1.cube`

,
`negf-8zgnr-0.3.curden_atom.xsf`

, `negf-8zgnr-0.3.scurden_atom.xsf`

,

are generated.
These files contain the following quantities:

*System.Name*`.curden.xsf`

,*System.Name*`.scurden.xsf`

These files contains the charge and the spin current density respectively on real space grids. They can be visualized using 'DisplayForces' in XCrySDen.

*System.Name*`.curden1.cube`

,*System.Name*`.scurden1.cube`

These files contains the

**a**-component of the charge and the spin current density respectively on real space grids. They can be visualized using VESTA, XCrySDen, etc.*System.Name*`.curden_atom.xsf`

,*System.Name*`.scurden_atom.xsf`

These files contains the charge and the spin current density respectively averaged in Voronoi polyhedra of each atoms. They can be visualized using 'DisplayForces' in XCrySDen.

NEGF.OffDiagonalCurrent on # default offin a input file for the calculation with the non-collinear magnetism, the following files are outputted.

*System.Name*`.odcurden_r.xsf`

,*System.Name*`.odcurden_i.xsf`

*System.Name*`.odcurden1_r.cube`

,*System.Name*`.odcurden1_i.cube`

*System.Name*`.odcurden_atom_r.xsf`

,*System.Name*`.odcurden_atom_i.xsf`

For example, the currentdensity in 8-zigzag graphene nanoribbon with an antiferromagnetic junction under a finite bias voltage of 0.3 V in Fig. 34. In the vicinity of boundaries, that shows an unphysical behavior because the basis set is not treated correctly in these regions. If you want to calculate more precisely the current density in these regions, please make a supercell larger.

2016-04-03