Anisotropic a-C:H from compression of polyacetylene

We have simulated the transformation of crystalline trans-polyacetylene into alpha-C:H under pressure by constant pressure ab initio molecular dynamics. Polyacetylene undergoes a gradual saturation of C-C bonds via chain interlinks, ending up at similar to 59 GPa with alpha-C:H containing 80% sp(3) carbon atoms. The sp(2) --> sp3 conversion is irreversible and does not reverse by returning to zero pressure. The final alpha-C:H is a wide gap insulator and, at variance with the conventionally generated alpha-C:H, is highly anisotropic keeping some memory of the original polyacetylene chain axis.