Pistack polymorphs (mol=25 atoms,
 total energies by PBE-D3paw900,
 band structure parameters* by CAM-B3LYPp2p):
---------------------------------------------
           dE     EGX   dEG
         meV/mol  eV    eV
---------------------------------------------
CAaac       0    2.23  0.50
AAaac       7    2.35  0.13
BAab       12    2.31  0.76
CAab       12    2.01  0.05
CBaac      15    2.11  0.38
CAaac+aac  25
BDa        28    2.29  0.13  also amorphous**
DAaac      31    2.53  0.54
BAaac      36    2.49  0.74
CAabab     43    1.94  0.32
BBaac      44    2.19  0.29
BAacc      46
CBab       55
BAa        56
BAa-min2   59
BDab       60
BBa        64
CBabab     70
BCa        78
ABaac     105    1.94  0.31
CA        105    2.07  0.48
C         113    2.46  0.49  also amorphous
CBb       116
CAb       118
CAa       127
CCa       137
B         150                also amorphous
CDa       153
CBa       169                also amorphous
AAa       181
---crystals---------------------------------------------------
iL         -1.4              fully relaxed interdigitated
i           0    2.29  0.13  monoclinic interdigitated
CA         86    2.19  0.40  Dudenko's structure relaxes to CA
C         127    2.46  0.52
--------------------------------------------------------------
* EGX=E1(X)-E1(Gamma), dEG=E1(Gamma)-E2(Gamma),
  where numbers enumerate eigenergies from top of VB
**Only 4 polymorphs with ordered backbone and disordered side chains
  can be obtained by melt-quench above 300K with force field [Moreno10]