4 Layers, Bottom 1 frozen, 10 A Vacuum, Lattice Constant used: 4.04105835927672, Dij = 2.333106131539414
  - 6x6x1
    D12 = 2.369563726339331                       |  1.5626 %
    D23 = 2.4173669382563783                      |  3.6115 %
    D34 = 2.3634286876386095                      |  1.2997 % 
    
    Layer Positions:
      [0.         2.36342869 4.78079563 7.15035935]

  - 7x7x1
    D12 = 2.2910639780492934                      | -1.8020 %
    D23 = 2.2033075064131085                      | -5.5633 %
    D34 = 2.2909047336045187                      | -1.8088 % 

    Layer Positions:
      [0.         2.29090473 4.49421224 6.78527622]

  - 8x8x1
    D12 = 2.335881463881365                       |  0.1190 % 
    D23 = 2.2338586295136253                      | -4.2539 %
    D34 = 2.336060205094546                       |  0.1266 %

    Layer Positions:
       [0.         2.33606021 4.56991883 6.9058003 ]

  - 9x9x1
    D12 = 2.342252846812282                       |  0.3920 %
    D23 = 2.2611446506640616                      | -3.0844 %
    D34 = 2.3446394993262962                      |  0.4943 %

    Layer Positions:
      [0.         2.3446395  4.60578415 6.948037  ]
  
  - 10x10x1
    D12 = 2.4126045619741987                      |  3.4074 %
    D23 = 2.384469407051891                       |  2.2015 %
    D34 = 2.417830030975291                       |  3.6314 %

    Layer Positions:
      [0.         2.41783003 4.80229944 7.214904  ]

  - 11x11x1
    D12 = 2.346964526983431                       |  0.5940 %
    D23 = 2.3532645026616454                      |  0.8640 %
    D34 = 2.344922775256633                       |  0.5065 %

    Layer Positions:
      [0.         2.34492278 4.69818728 7.0451518 ]

  - 12x12x1
    D12 = 2.3276746215124193                      | -0.2328 %
    D23 = 2.2500058601212145                      | -3.5618 %
    D34 = 2.326360013975799                       | -0.2891 %

    Layer Positions:
      [0.         2.32636001 4.57636587 6.9040405 ]

  - 20x20x1
    D12 = 2.374107412645338                       |  1.7574 %
    D23 = 2.306912905815851                       | -1.1227 %
    D34 = 2.3710400490800203                      |  1.6259 %

    Layer Positions:
      [0.         2.37104005 4.67795295 7.05206037]


4 Layers, Bottom 2 frozen 10 A Vacuum, Lattice Constant used: 4.04105835927672, Dij = 2.333106131539414
  - 6x6x1
    D12 = 2.377191037187723                       |  1.8895 %
    D23 = 2.4280655286918917                      |  4.0701 %
    D34 = 2.3331061315393637                      |  0.0000 %

    Layer Positions:
      [0.         2.33310613 4.76117166 7.1383627 ]
    
  - 7x7x1
    D12 = 2.2878885334558428                      | -1.9381 %
    D23 = 2.1989441399728125                      | -5.7504 %
    D34 = 2.3331061315393637                      |  0.0000 % 

    Layer Positions:
      [0.         2.33310613 4.53205027 6.8199388 ]
    
  - 8x8x1
    D12 = 2.336006521322573                       |  0.1243 %
    D23 = 2.2311876813544855                      | -4.3684 %
    D34 = 2.3331061315393637                      |  0.0000 %

    Layer Positions:
      [0.         2.33310613 4.56429381 6.90030033]
 
  - 9x9x1
    D12 = 2.3392469918466574                      |  0.2632 %
    D23 = 2.256615022015161                       | -3.2785 %
    D34 = 2.3331061315393637                      |  0.0000 %

    Layer Positions:
      [0.         2.33310613 4.58972115 6.92896815]
   
  - 10x10x1
    D12 = 2.397282699890396                       |  2.7507 %
    D23 = 2.3271755512587124                      | -0.2542 %
    D34 = 2.3331061315393637                      |  0.0000 %

    Layer Positions:
      [0.         2.33310613 4.66028168 7.05756438]
    
  - 11x11x1
    D12 = 2.3433798979102445                      |  0.4403 %
    D23 = 2.3527215688118344                      |  0.8407 %
    D34 = 2.3331061315393637                      |  0.0000 %

    Layer Positions:
      [0.         2.33310613 4.6858277  7.0292076 ]
    
  - 12x12x1
    D12 = 2.3310269744434615                      | -0.0891 %
    D23 = 2.2532599735310535                      | -3.4223 %
    D34 = 2.3331061315393637                      |  0.0000 %

    Layer Positions:
      [0.         2.33310613 4.58636611 6.91739308]
   
  - 20x20x1
    D12 = 2.37595646108101                        |  1.8366 %
    D23 = 2.305978166296843                       | -1.1627 %
    D34 = 2.3331061315393637                      |  0.0000 %

    Layer Positions:
       [0.         2.33310613 4.6390843  7.01504076]
    

5 Layers, Bottom 1 frozen, 10 A Vacuum, Lattice Constant used: 4.04105835927672, Dij = 2.333106131539414
  - 6x6x1
    D12 = 2.3680958806684522                      |  1.4997 %
    D23 = 2.3809484017575935                      |  2.0506 %
    D34 = 2.3803486950711346                      |  2.0249 %
    D45 = 2.3662435285976917                      |  1.4203 %

    Layer Positions:
      [0.         2.36624353 4.74659222 7.12754063 9.49563651]

  - 7x7x1
    D12 = 2.27602854127308                        | -2.4464 %
    D23 = 2.276152832730955                       | -2.4411 %
    D34 = 2.275185818861757                       | -2.4825 %
    D45 = 2.2728255140827396                      | -2.5837 %

    Layer Positions:
      [0.         2.27282551 4.54801133 6.82416417 9.10019271]

  - 8x8x1
    D12 = 2.398306362670578                       |  2.7946 % 
    D23 = 2.335443912167687                       |  0.1002 %
    D34 = 2.335866090149377                       |  0.1183 %
    D45 = 2.39962900966699                        |  2.8513 %

    Layer Positions:
      [0.         2.39962901 4.7354951  7.07093901 9.46924537]

  - 9x9x1
    D12 = 2.3956542283188087                      |  2.6809 %
    D23 = 2.3599826486877387                      |  1.1520 %
    D34 = 2.353423764603809                       |  0.8708 %
    D45 = 2.388869742854541                       |  2.3901 %

    Layer Positions:
      [0.         2.38886974 4.74229351 7.10227616 9.49793038]

  - 10x10x1
    D12 = 2.3771926734242372                      |  1.8896 %
    D23 = 2.3561345929606423                      |  0.9870 %
    D34 = 2.3560039706722704                      |  0.9814 %
    D45 = 2.3768515320693333                      |  1.8750 %

    Layer Positions:
      [0.         2.37685153 4.7328555  7.0889901  9.46618277]

  - 11x11x1
    D12 = 2.3742474744607485                      |  1.7634 %
    D23 = 2.296829816735447                       | -1.5549 %
    D34 = 2.2961448626279397                      | -1.5842 %
    D45 = 2.3735382521451758                      |  1.7330 %

    Layer Positions:
      [0.         2.37353825 4.66968311 6.96651293 9.34076041]

  - 12x12x1
    D12 = 2.384958143786161                       |  2.2224 %
    D23 = 2.339061107423877                       |  0.2552 %
    D34 = 2.337569688151841                       |  0.1913 %
    D45 = 2.3805662613612424                      |  2.0342 %

    Layer Positions:
      [0.         2.38056626 4.71813595 7.05719706 9.4421552 ]

  - 20x20x1
    D12 = 2.3937030759789995                      |  2.5973 %
    D23 = 2.3591458497080966                      |  1.1161 %
    D34 = 2.3580840381358743                      |  1.0706 %
    D45 = 2.3915510273760634                      |  2.5050 % 

    Layer Positions:
      [0.         2.39155103 4.74963507 7.10878092 9.50248399]


5 Layers, Bottom 2 frozen, 10 A Vacuum, Lattice Constant used: 4.04105835927672, Dij = 2.333106131539414
  - 6x6x1
    D12 = 2.3761567371927397                      |  1.8452 %
    D23 = 2.395740797941664                       |  2.6846 %
    D34 = 2.376174381416246                       |  1.8460 %
    D45 = 2.333106131539414                       |  0.0000 %

    Layer Positions:
      [0.         2.33310613 4.70928051 7.10502131 9.48117805]

  - 7x7x1
    D12 = 2.280089183006579                       | -2.2724 %
    D23 = 2.273440343514606                       | -2.5574 %
    D34 = 2.2693459802220532                      | -2.7328 %
    D45 = 2.333106131539414                       |  0.0000 %

    Layer Positions:
      [0.         2.33310613 4.60245211 6.87589246 9.15598164]

  - 8x8x1
    D12 = 2.4042133570788824                      |  3.0477 %
    D23 = 2.346832530770305                       |  0.5883 %
    D34 = 2.3541646038484947                      |  0.9026 %
    D45 = 2.333106131539414                       |  0.0000 %

   Layer Positions:
     [0.         2.33310613 4.68727074 7.03410327 9.43831662]

  - 9x9x1
    D12 = 2.4055361143988483                      |  3.1044 %
    D23 = 2.374733204753671                       |  1.7842 %
    D34 = 2.3497847962522656                      |  0.7149 %
    D45 = 2.333106131539414                       |  0.0000 %

    Layer Positions:
      [0.         2.33310613 4.68289093 7.05762413 9.46316025]

  - 10x10x1
    D12 = 2.3764556686146516                      |  1.8580 %
    D23 = 2.358359068710925                       |  1.0824 %
    D34 = 2.357854922242793                       |  1.0608 %
    D45 = 2.333106131539414                       |  0.0000 %

    Layer Positions:
      [0.         2.33310613 4.69096105 7.04932012 9.42577579]

  - 11x11x1
    D12 = 2.380615312706671                       |  2.0363 %
    D23 = 2.2971515778182106                      | -1.5411 %
    D34 = 2.2948267518178973                      | -1.6407 %
    D45 = 2.333106131539414                       |  0.0000 %

    Layer Positions:
      [0.         2.33310613 4.62793288 6.92508446 9.30569977]

  - 12x12x1
    D12 = 2.3869395706245093                      |  2.3074 %
    D23 = 2.3275728765446138                      | -0.2372 %
    D34 = 2.3252193995004156                      | -0.3380 %
    D45 = 2.333106131539414                       |  0.0000 %

    Layer Positions:
      [0.         2.33310613 4.65832553 6.98589841 9.37283798]

  - 20x20x1  
    D12 = 2.3980363438676617                      |  2.7830 %
    D23 = 2.364516920695703                       |  1.3463 %
    D34 = 2.360605309117581                       |  1.1787 %
    D45 = 2.333106131539414                       |  0.0000 %

    Layer Positions:
      [0.         2.33310613 4.69371144 7.05822836 9.45626471]


Static 4 Layers, Bottom 2 frozen, 15 A vacuum, Lattice Constant used: 4.04105835927672, Dij = 2.333106131539414
    Done by Minimizing a Z1 by Z2 grid (-0.2, 0.3 A) computed with static single points

  - 20x20x1
    D12 = 2.37602                                 |  1.8393 %
    D23 = 2.30600                                 | -1.1616 %
    D34 = 2.333106131539414                       |  0.0000 %

    Layer Position:
      [0.         2.3331061315 4.63911 7.01513 ]

  - 24x24x1
    D12 = 2.37362                                 |  1.7365 %
    D23 = 2.300034                                | -1.4175 %
    D34 = 2.333106131539414                       |  0.0000 %

    Layer Position: 
      [0.         2.3331061315 4.63314 7.00676 ]

  -25x25x1
    D12 = 2.35456                                 |  0.9195 %
    D23 = 2.28610                                 | -2.0146 %
    D34 = 2.333106131539414                       |  0.0000 %

    Layer Position:
      [0.         2.3331061315 4.61921 6.97377]


Experiments:
  - F. Jona et. al., 1980, J. Phys. C: Solid State Phys., 13 
    D12 =                                         |  2.2 %

    LEED results, at RT surface temperature


  - H. B. Nielson et. al., 1982, J. Phys. C; Solid State Phys., 15
    D12 =                                         |  0.9 +- 0.5 %

    LEED results, At 90 K Surface Temperature


  - J.R. Noonan et. al., 1990, Journal of Vacuum Science & Technology A 8.
    D12 =                                         |  1.7 +- 0.3 %
    D23 =                                         |  0.5 +- 0.7 %

    LEED I - V Spectra at 160 K surface Temperature

    D12 =                                         |  1.8 %
    D23 =                                         |  0.1 %

    LEED I- V Spectra at RT surface temparaute


Other Theory:
  - J. Schochlin et. al., 1994, Surface Science, 324;
    D12 =                                         |  1.18 %
    D23 =                                         | -0.40 %
    D34 =                                         |  0.22 % 

    LDA

  - N. Gerrits et. al. 2020, J. Phys. Chem. Lett, 11;
    D12 =                                         | 1.4 %

    HSE03-1/3x 8x8x1 Kpoints 400 eV cutoff 

