Quantum Chemical Investigation of Molecules in External Electric Fields

The use of oriented external electric fields (OEEFs) as a way to manipulate molecular bonds has recently gained popularity. Being a form of chemical catalysis, they can selectively change bond strengths and induce reactions. This has potential applications in mechanochemistry, a field that studies the application of mechanical force to selectively rupture bonds. This work investigates the accuracy of computational methods based on density functional theory (DFT) for calculating electronic structures in strong OEEFs. Through a broad benchmark study, the performance of various DFT methods for this application is quantified. Subsequently, the methodology is combined with a computational model applying mechanical force. The first ever computational investigation of the rupture behaviour of a mechanophore in an OEEF concludes that OEEFs can drastically alter the force required to rupture a mechanophore's scissile bond. Following that, a study of a mechanophore subjected to an OEEF in a simulated thermal environment shows that the effects that OEEFs have on the molecular structure are largely temperature-independent, even when mechanical force is applied.