SCL's Nenad Vukmirovic presented a seminar:

"Overlapping fragments method for electronic structure calculations of large semiconducting systems"

Abstract:

We present a method for the calculation of the electronic structure of semiconducting systems that contain tens of thousands of atoms. The method is based on the division of the system into mutually overlapping fragments and the representation of the single-particle Hamiltonian in the basis of eigenstates of these fragments. In practice, for the range of the system size that we studied (up to tens of thousands of atoms), the dominant part of the calculation scales linearly with the size of the system when all the states within a fixed energy interval are required [1].

The method was then applied to calculate the electronic states in disordered semiconducting polymers. We find that the hole states are localized due to the fluctuations of the electrostatic potential and not by the breaks in the conjugation of the polymer chain. The tail of the density of hole states exhibits an exponentially decaying behavior [2].

[1] N. Vukmirović and L.-W. Wang, J. Chem. Phys. 134, 094119 (2011).
[2] N. Vukmirović and L.-W. Wang, J. Phys. Chem. B 115, 1792 (2011).