# Modified embedded atom method (MEAM) potential with user defined functions¶

This example demonstrates the use of the modified embedded atom method (MEAM) potential routine together with user defined functions. The potential form and parameters have been taken from [LenSadAlo00]. The example also illustrates the use of XML Inclusions. Note that the potential is merely evaluated for a couple of simple lattice structures and none of the parameters are fitted.

## Location¶

examples/potential_MEAM

## Input files¶

• main.xml: main input file

  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20  Silicon MEAM potential by Lenosky et al. medium Si 
• potential.xml: potential parameter set (included in main input file via XML Inclusions)

  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97  -42.66967 4.5 -1.0 3.5 -3.61894 3.5 -13.95042 1.13462 0.73514 0.61652 
• structures.xml: input structures (included in main input file via XML Inclusions)

  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96  Si 3.6 Si 3.0 Si 2.6 2.1 Si 2.6 1.1 Si 5. Si Si 3. 1.6 0.375 

## Output (files)¶

• The final properties (as well as parameters) are written to standard output.

  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 This is program version 0.1.6 Reading job file main.xml ------------------------------------------------------- Parsing input file(s) ------------------------------------------------------- ------------------------------------------------------- Computing structure properties Structure 'A1 (fcc)': total-energy: -3.91431 eV atomic-energy: -3.91431 eV/atom total-volume: 16.0672 A^3 atomic-volume: 16.0672 A^3/atom bulk-modulus: 8688.3 GPa lattice-parameter: 4.00559 A (relaxed) [0:] Structure 'A2 (bcc)': total-energy: -3.8948 eV atomic-energy: -3.8948 eV/atom total-volume: 15.4127 A^3 atomic-volume: 15.4127 A^3/atom bulk-modulus: 8729.77 GPa lattice-parameter: 3.13547 A (relaxed) [0:] Structure 'A3 (hcp) - large c/a': total-energy: -7.89209 eV atomic-energy: -3.94605 eV/atom total-volume: 30.7255 A^3 atomic-volume: 15.3627 A^3/atom bulk-modulus: 5891.52 GPa lattice-parameter: 2.58945 A (relaxed) ca-ratio: 2.04336 (relaxed) Structure 'A3 (hcp) - small c/a': total-energy: -8.64158 eV atomic-energy: -4.32079 eV/atom total-volume: 27.8554 A^3 atomic-volume: 13.9277 A^3/atom bulk-modulus: 5049.82 GPa lattice-parameter: 3.07713 A (relaxed) ca-ratio: 1.10393 (relaxed) Structure 'A4 (diamond)': total-energy: -9.22485 eV atomic-energy: -4.61242 eV/atom total-volume: 40.0378 A^3 atomic-volume: 20.0189 A^3/atom bulk-modulus: 110.009 GPa lattice-parameter: 5.43055 A (relaxed) [0:] Structure 'hexagonal diamond': total-energy: -18.4867 eV atomic-energy: -4.62167 eV/atom total-volume: 80.0477 A^3 atomic-volume: 20.0119 A^3/atom bulk-modulus: 112.553 GPa lattice-parameter: 3.84095 A (relaxed) [0:] ca-ratio: 1.63118 (relaxed) u-parameter: 0.375008 (relaxed) ------------------------------------------------------- -------------------------------------------------------