2016/01/01 by E. Mostaani, B. Monserrat, N. D. Drummond +1
Chemistry · Materials Science · Physics and Astronomy · #Advanced Physical and Chemical Molecular Interactions #Band gap #Exciton #Fick's laws of diffusion #Fullerene Chemistry and Applications #Lattice (music) #Organic and Molecular Conductors Research #Phonon #Quantum Monte Carlo #Quasiparticle #Raman spectroscopy #cond-mat.mes-hall
paper · pdf · doi:10.1039/c5cp07891a
published as Physical Chemistry Chemical Physics, 2016, 18, 14810 - 14821 · 13 pages and 14 figures
openalex publication_date 2016/01/01 · arxiv created 2016/04/08 · arxiv updated 2016/06/03 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We report diffusion quantum Monte Carlo (DMC) calculations of the quasiparticle and excitonic gaps of hydrogen-terminated oligoynes and extended polyyne. The electronic gaps are found to be very sensitive to the atomic structure in these systems. We have therefore optimised the geometry of polyyne by directly minimising the DMC energy with respect to the lattice constant and the Peierls-induced carbon-carbon bond-length alternation. We find the bond-length alternation of polyyne to be 0.136(2) Å and the excitonic and quasiparticle gaps to be 3.30(7) and 3.4(1) eV, respectively. The DMC zone-centre longitudinal optical phonon frequency of polyyne is 2084(5) cm(-1), which is consistent with Raman spectroscopic measurements for large oligoynes.