Hund file

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

Note

For spinless fermion models (CalcModel=7, 8), Hund interactions have no physical meaning since there are no spin degrees of freedom. Specifying this file for spinless fermion models will result in an error.

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

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.