LOW-ENERGY STRUCTURES OF A MONOLAYER OF OCTADECANETHIOL SELF-ASSEMBLED ON AU(111)

The methods of stochastic global search and static energy minimization are employed to explore the configurational space of a monolayer of octadecanethiol, CH3(CH2)(17)SH, self-assembled on Au(111). In the calculation of the interaction of the sulfur head group with the gold surface, four different force fields are tried, including the ones fitted to ab initio quantum chemical data. The calculations show that the alkanethiol/gold monolayer system is much richer in low-energy minima than it was found in the previous computer simulations. The stable monolayer structures within 1 kcal/mol of the ground state are described and discussed in detail.