Herringbone polymorphs by PBE-D3paw900 (total energies in meV/mol, mol=7 atoms, P212121*=P212121:084yx):
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     SG       V1    23s4  RMSD   phi    xi2   y2    z3    d      xi    Eacc   E   ZPE  E(T) F(T)  frequenc  elastic eigenval
             Ao^3          Ao    deg          Ao    Ao    Ao            meV  meV  meV  meV  meV   meV  meV    GPa  GPa  GPa
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a   P21/nxz  11.60  00+0  .014  62.02  0.301 7.527 5.544 4.674  0.150   0.0  0.0  0.0  0.0  0.0   3.74 7.42   1.89 2.41 5.73
c   P212121* 11.58  00-+  .039  66.03   0    7.238 5.752 4.623   1/4    2.5  2.9  1.7  2.6  2.3   1.90 6.52 -16.74 0.30 0.46
b   P21/cxz  11.58  00-0  .009 -69.40 -0.378 7.065 5.891 4.599 -0.189   6.1  6.4  4.7  6.2  5.3  -1.71 6.00   0.83 0.88 3.25
aH  Pmcn     11.65  00+0  .030  64.39   0    7.428 5.641 4.663   0     11.2 11.2  9.4  4.0  9.2  -2.90 6.67  -0.86 0.55 4.76
bH  Pmnb     11.86  00-0  .012 -63.12   0    7.559 5.642 4.716   0     24.3 24.7 21.9 23.5 22.0   1.59 4.20  -0.35 0.57 3.22
-----Shifted----------------------------------------------------------------------------------------------------------------
ax  P21/nxz  11.61  00+0  .015  62.30  0.285 7.517 5.553 4.673  0.143   0.1  0.1 -0.3  0.0 -0.6   3.44 7.15   0.53 1.12 2.87
ay  P21/nxz  11.65  00+0  .012  62.26   1/3  7.527 5.564 4.680   1/6    0.5
-----Oligomers--------------------------------------------------------------------------------------------------------------
     SG       V1    23s4  RMSD    phi    xi2   y2    z3    d      xi     z2     xi3   file
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o2  P21/c    11.72  +0-+  .230  59.77  0.370 7.583 5.652 4.599  0.152  -0.447 -0.066  bithiophene/cryst_PBE-D3paw900
o4  P21/cxz  11.73  +0-+  .086  62.59  0.371 7.486 5.647 4.667  0.180  -0.072 -0.011  oligothiophene4/cryst_PBE-D3paw900
o6  P21/cxz  11.70  +0-+  .075  62.19  0.343 7.498 5.605 4.672  0.169  -0.031 -0.004  oligothiophene6/cryst_PBE-D3paw900
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Polymorph notations:
a - in-phase
b - anti-phase
c - in-phase zigzag
H - high-symmetry