(65ak) Evaluation of a Molecular Spring Nanothermometer

Classical molecular dynamics (MD) simulations are used to evaluate the feasibility of a molecular spring nanothermometer. A system composed of a gold slab of six layers and four thiolated polyethylene glycol (PEG) molecules, was located in a central simulation box and repeated periodically to represent the self-assembly of PEG molecules on the gold surface. The interactions between gold and PEG were obtained from density functional theory (DFT) simulations and correlated with a Morse effective force field model. It is known that the (111) surface of a gold crystal is the lowest in energy, for this reason our system has this surface exposed to PEG. The simulations were performed in DLPOLY 2.20 at temperatures between 293 K and 333 K. This was done to obtain information that would help us evaluate the ability of the system as a thermometer in biologically favorable temperatures. The velocity autocorrelation function (VACF) for each simulation was obtained and Fourier transformed to find vibrational spectra at different temperatures. Analysis of these calculated spectra may permit to get some insights into the design of practical devices where the variation of vibrational modes produces different luminescence at each temperature, which is the principal characteristic of this nanothermometer.