Electronic structure predictions for properties of organic materials
Contributors: Aspuru-Guzik, Alan; Heller, Eric; Cohen, Adam
Published: 2012
Language: eng
Description: Electronic structure calculations of organic molecules are an important set of tools to gain understanding of molecular structures. This thesis presents two separate contributions to applying quantum chemistry to organic molecules. In the first section, the computational cost of a post-Hartree-Fock method is improved for large molecules by using graphical processing units. In this work, the resolution-of-the-identity second- order Møller-Plesset perturbation theory (RI-MP2) algorithm was adapted to send the large matrix multiplication steps to be run on a graphics co-processor. As a result, the calculations were performed up to 15x faster than a standard implementation for large molecules such as taxol. In the second section of the thesis, density functional theory is used to predict the molecular dipole moments of molecules that form self-assembled monolayers (SAMs) on metal surfaces. The dipole moment of the molecule that is aligned perpendicular to the surface in a SAM changes the work function of the surface. The calculated dipole moments correlate with the current density measured for the junctions by experimental collaborators. This result holds for a series of alkane chains with even and odd numbers of carbons and for molecules that have an amide group substituted for an ethylene unit.
Notes: Keywords: electronic structure, graphics cards, self-assembled monolayers.

Thesis Ph.D. Harvard University 2012