Quantum control of optoelectronic and thermodynamic properties of dopamine molecule in external electric field : A DFT and TD-DFT study

The effect of external electric field on molecular properties of dopamine is investigated using DFT and TD-DFT methods with B3LYP functional and 6-311++G(d,p) basis set. Optoelectronic properties (energy, polarizability, molecular orbitals, HOMO-LUMO gap, optical gap, electron-hole binding energy, UV-visible and electroabsorption spectra), and thermodynamic properties (zero-point vibrational energy, thermal energy, entropy, and specific heat capacity) were investigated. These properties are useful in developing molecular sensing devices, and understanding molecule receptor binding interaction. Our results using TD-DFT for excited states show that when an extemal electric field of magnitude F = 0.020 a.u. is applied along the x-axis, there is a shift in the absorption spectra of dopamine from the ultraviolet to the visible region which will be useful in optogenetic stimulation using visible light. The tunneling ionization rate increases and tunneling ionization time decreases with increase in electric field. These studies have potential applications in many of the emerging technologies in neurobiology such as deep brain stimulation and iontophoresis.