<SW_params n_types="2" label="DFTB_Si_H_elastic_fit">
<comment> generated by merlin fitting code, fit to DFTB elastic constants for C (dia), Si (dia), SiC (3C) </comment>
<per_type_data type="1" atomic_num="1" />
<per_type_data type="2" atomic_num="14" />

<!-- Si-Si, from fit -->
<per_pair_data atnum_i="14" atnum_j="14" AA="7.04967303917887" BB="0.944258760041191" 
      p="4.04633491076025" q="-5.410078791511558E-02" a="1.51930392640520" 
      sigma="2.13527699552411" eps="2.17025002373649" />

<!-- H stuff, fiddled by hand -->
<per_pair_data atnum_i="1" atnum_j="1" AA="0.0" BB="0.0"
      p="0" q="0" a="1.0" sigma="1.0" eps="0.0" />
<per_pair_data atnum_i="1" atnum_j="14" AA="8.581214" BB="0.0327827"
      p="4" q="0" a="1.25" sigma="2.537884" eps="2.1672" />

<!-- triplet terms: atnum_c is the center atom, neighbours j and k -->

<!-- Si-Si-Si, from fit -->
<per_triplet_data atnum_c="14" atnum_j="14" atnum_k="14" 
      lambda="21.0055333190804" gamma="0.651249471076724" eps="2.22344583669553" />

<!-- H stuff, fiddled by hand -->
<per_triplet_data atnum_c="1"  atnum_j="1"  atnum_k="1"
      lambda="21.0" gamma="1.20" eps="2.1675" />
<per_triplet_data atnum_c="1"  atnum_j="1"  atnum_k="14"
      lambda="21.0" gamma="1.20" eps="2.1675" />
<per_triplet_data atnum_c="1"  atnum_j="14" atnum_k="14"
      lambda="21.0" gamma="1.20" eps="2.1675" />

<per_triplet_data atnum_c="14" atnum_j="1"  atnum_k="1"
      lambda="21.0" gamma="1.20" eps="2.1675" />
<per_triplet_data atnum_c="14" atnum_j="1"  atnum_k="14"
      lambda="21.0" gamma="1.20" eps="2.1675" />
<per_triplet_data atnum_c="14" atnum_j="14" atnum_k="14"
      lambda="21.0" gamma="1.20" eps="2.1675" />

</SW_params>
