Simulation of nonlinear optical properties of voltage-sensitive dyes

Second-harmonic generation (SHG) microscopy is an important optical imaging technique with great potential in the biological and medical fields, as it uses low-energy incident light that reduces cellular damage. One of its most interesting applications is in neuroscience, where SHG voltage-sensitive dyes can be used to monitor neuronal activity in vivo. Despite experimental efforts, progress in this field is slow, as computational quantum chemistry support is also limited by the complexity of biological structures and the precision of quantum chemistry methods.

The current project aims to move forward in this direction by simulating the effects of membrane potentials on the (nonlinear) optical responses of organic dyes used today to monitor neural activity. Density Functional Theory (DFT) and Time-Dependent (TD)-DFT will be the quantum chemical methods used to explore the systems due to their size and complexity. Different model systems will be used to study electrostatic-potential effects, ranging from isolated dyes to simplified representations of dyes within a neuron’s membrane. From these simulations, possible relationships between electronic structure and optical response will be characterized.

Ideal candidates should have a background in chemistry or physics and knowledge of computational chemistry and electronic structure theory of molecules. They will become acquainted with electron delocalization, optical response, and different quantum-chemical methods and their limitations.