4.2.9. Hund file

This file determines the values of Hund couplings \(J_{ij}^{\rm Hund}\) (for \(S=1/2\) system),

\[\mathcal H+=-\sum_{i,j}J_{ij}^{\rm Hund} (n_{i\uparrow}n_{j\uparrow}+n_{i\downarrow}n_{j\downarrow}).\]

An example of the file format is as follows.

======================
NHund 6
======================
========Hund ======
======================
   0     1 -0.250000
   1     2 -0.250000
   2     3 -0.250000
   3     4 -0.250000
   4     5 -0.250000
   5     0 -0.250000

File format

• Line 1: Header
• Line 2: [string01] [int01]
• Lines 3-5: Header
• Lines 6-: [int02] [int03] [double01].

Parameters

• [string01]

  Type : String (a blank parameter is not allowed)

  Description : A keyword for the total number of Hund couplings. You can freely give a name to the keyword.

• [int01]

  Type : Int (a blank parameter is not allowed)

  Description : An integer giving the total number of Hund couplings.

• [int02], [int03]

  Type : Int (a blank parameter is not allowed)

  Description : An integer giving a site index (\(0<=\) [int02], [int03] \(<\) Nsite).

• [double01]

  Type : Double (a blank parameter is not allowed)

  Description : A value for \(J_{ij}^{\rm Hund}\).

Use rules

• Headers cannot be omitted.
• A program is terminated when the components of the Hund couplings are double counted.
• A program is terminated when [int01] is different from the total number of Hund couplings defined in this file.
• A program is terminated when either [int02] or [int03] is outside the range of the defined values.