DFT simulation

Primary investigator: Arvidas Tamulis, Vilnius University, Lithuania.

The natural and artificial living cells and their substructures are self-assembling due to electron correlation interactions among biological and water molecules which leads to the appearance of attractive dispersion forces and hydrogen bonds. Dispersion forces  are weak intermolecular forces that arise from the attractive force between quantum multipoles. A hydrogen bond is a special type of quantum attractive interaction that exists between an electronegative atom and a hydrogen atom bonded to another electronegative atom and this hydrogen atom exists in two quantum states. The most accurate method to simulate these dispersion forces and hydrogen bonds is to perform quantum mechanical non-local density functional potential (DFT) calculations. In this project, we have simulated micellar aggregates consisting of water, fatty acids, short peptide nucleic acid (PNA) strands and Ru(II)(bpy)2. The cell systems studied are based on peptide nucleic acid and are 3.0 - 4.2 nm in diameter. The electron tunneling and associated light absorption of most intense transitions as calculated by the time dependent density functional theory method differs from spectrosopic experiments by only 0.2 - 0.3 nm, which are within the value of experimental errors. This agreement implies that the quantum mechanically self-assembled structure of artificial minimal living cells very closely approximate the realistic one.

A. Tamulis, V. Tamulis, H. Ziock, S. Rasmussen, “Influence of Water and Fatty Acid Molecules on Quantum Photoinduced Electron Tunnelling in Photosynthetic Systems of PNA Based Self-Assembled Protocells”, Chapter #2 in book “Multi-scale Simulation Methods for Nanomaterials”, eds. R. Ross and S. Mohanty, John Wiley & Sons, Inc., New Jersey, pages 9-28, January 2008.