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12: Benzene — Valence and low-lying conduction states

Image title
Benzene molecule in periodic cell plotted with the XCrySDen program.

Valence States

  • Outline: Obtain MLWFs for the valence bands of benzene.

  • Items 1-4: Inspect the output file benzene.wout. The total spread converges to its minimum value after just a few iterations.

    Convergence of total spread \(\Omega\) is shown in Figure 2. The spread converges very quickly, and after only 15 iterations the \(|\Delta\Omega|\) is already below \(10^{-8}\).

    Image title
    Convergence of total spread \(\Omega\). The red curve refers to the left y-axis, i.e. the actual value of the total spread at each iteration. The blue curve refers to the right y-axis, i.e. the absolute difference between between the spread functional at iteration \(i\) and \(i-1\), i.e. \(\Delta\Omega\).

    Below is shown the final state of the minimization, after 22 iterations:

    Output file
     Final State
      WF centre and spread    1  ( -6.875141,  7.935472,  7.937658 )     0.65233309
      WF centre and spread    2  (  4.748245,  7.935472,  7.937658 )     0.65234300
      WF centre and spread    3  (  5.809324,  6.097678,  7.937658 )     0.65186298
      WF centre and spread    4  (  7.816785, -7.396927,  7.648002 )     1.20135958
      WF centre and spread    5  (  7.816785, -7.396927, -7.648002 )     1.20135948
      WF centre and spread    6  (  7.936083,  7.324218, -7.937658 )     0.60992987
      WF centre and spread    7  (  7.935073, -6.095184,  7.937658 )     0.65161009
      WF centre and spread    8  (  6.874208, -6.712573,  7.937658 )     0.61134798
      WF centre and spread    9  (  6.874224,  6.850489, -7.648754 )     1.20500764
      WF centre and spread   10  ( -7.936214,  6.097679,  7.937658 )     0.65186256
      WF centre and spread   11  (  5.813353, -6.095183,  7.937658 )     0.65160955
      WF centre and spread   12  (  6.874224,  6.850489,  7.648754 )     1.20500766
      WF centre and spread   13  (  5.812342,  7.324217,  7.937658 )     0.60993084
      WF centre and spread   14  (  5.931632, -7.396946,  7.648001 )     1.20136423
      WF centre and spread   15  (  5.931632, -7.396946, -7.648001 )     1.20136424
      Sum of centres and spreads ( 71.362557,  7.925029, 55.563607 )    12.95829277
    
             Spreads (Ang^2)       Omega I      =    10.455434168
            ================       Omega D      =     0.000000000
                                   Omega OD     =     2.502858604
        Final Spread (Ang^2)       Omega Total  =    12.958292772
     ------------------------------------------------------------------------------
    
  • Item 5: Plot the MLWFs 2-4.

    MLWFs are shown in Figure 3.

    Valence MLWF 2 Valence MLWF 3 Valence MLWF 4

    MLWFs 2, 3 and 4, with Vesta from cube format.

Valence + Conduction States

  • Outline: Obtain MLWFs for the valence and low-lying conduction states of benzene.

  • Item 1: First, we minimise \(\Omega_I\). Then, we minimise \(\Omega_D + \Omega_{OD}\).

    Extract from the .wout output file for the disentanglement procedure with initial and final value of \(\Omega_I\)

    Output file
                       Extraction of optimally-connected subspace
                       ------------------------------------------
     +---------------------------------------------------------------------+<-- DIS
     |  Iter     Omega_I(i-1)      Omega_I(i)      Delta (frac.)    Time   |<-- DIS
     +---------------------------------------------------------------------+<-- DIS
           1      14.77292507      14.36793746       2.819E-02      0.06    <-- DIS
           .  .     .    .    .
           .  .     .    .    .
          76      14.26979011      14.26979011       7.234E-11      0.34    <-- DIS
    
                 <<<      Delta < 1.000E-10  over  3 iterations     >>>
                 <<< Disentanglement convergence criteria satisfied >>>
    
            Final Omega_I    14.26979011 (Ang^2)
    
     +----------------------------------------------------------------------------+
    

    Below a snippet from the .wout output file, showing the finale state of the minimisation of \(\Omega_D\) and \(\Omega_{OD}\).

    Output file
     Final State
      WF centre and spread    1  ( -6.872991, -7.937658,  7.937657 )     0.64685210
      WF centre and spread    2  ( -7.937084, -6.094542, -7.937656 )     0.64620663
      WF centre and spread    3  (  5.810194, -6.094542,  7.937654 )     0.64620672
      WF centre and spread    4  (  4.746097, -7.937658,  7.937657 )     0.64685949
      WF centre and spread    5  (  5.810193,  6.094541, -7.937657 )     0.64620720
      WF centre and spread    6  ( -7.937083,  6.094541,  7.937655 )     0.64620743
      WF centre and spread    7  (  6.874209,  6.725491,  7.937658 )     0.58709128
      WF centre and spread    8  (  6.874209, -6.725491,  7.937657 )     0.58709059
      WF centre and spread    9  (  5.824168, -7.331141,  7.937657 )     0.58581741
      WF centre and spread   10  (  5.824168,  7.331141, -7.937658 )     0.58581778
      WF centre and spread   11  (  7.924257,  7.331142,  7.937657 )     0.58581692
      WF centre and spread   12  (  7.924257, -7.331141, -7.937658 )     0.58581674
      WF centre and spread   13  ( -7.514755,  7.937658, -7.937656 )     1.57077288
      WF centre and spread   14  (  7.622957, -6.642249,  7.937655 )     1.58413409
      WF centre and spread   15  (  6.125499, -6.642276, -7.937651 )     1.58406298
      WF centre and spread   16  (  5.387848, -7.937658, -7.937656 )     1.57079972
      WF centre and spread   17  (  6.125498,  6.642275,  7.937656 )     1.58407213
      WF centre and spread   18  (  7.622957,  6.642249, -7.937653 )     1.58414266
      Sum of centres and spreads ( 60.234596,-15.875317, 15.875317 )    16.87397474
    
             Spreads (Ang^2)       Omega I      =    14.269790106
            ================       Omega D      =     0.000000000
                                   Omega OD     =     2.604184635
        Final Spread (Ang^2)       Omega Total  =    16.873974742
     ------------------------------------------------------------------------------
    
  • Item 2: Plot the MLWFs 1, 7 and 13.

    MLWFs are shown in Figure 4.

    Valence MLWF 1 Valence MLWF 7 Conduction MLWF 13

    MLWFs 1, 7 and 13 with Vesta from cube format.