Quantum Chemical Studies on Atomic-scale Tribology

In this thesis quantum chemical methods have been§applied to study the tribology of§methylated diamond and cubic and hexagonal boron§nitride. Interaction energies between §surfaces have been calculated from which friction§coefficients are derived. The influence §of the size and the nature of the model representing§the surface have been examined.§§The use of periodic models for friction studies has §advantages. Periodic models§circumvent the difficulties typical to cluster models§and produce friction coefficients in close agreement§with experimental studies. The studied case of ice-Ih§sliding on h-BN represents a novel application of§periodic quantum chemical methods for heterogeneous§friction system. Tribochemical reactions were found§to occur in methylated diamond on methylated diamond§and in ice-Ih on h-BN sliding. B3LYP method was shown§to be appropriate for friction and tribochemical§reaction studies. §§The studies of diamond, c-BN and h-BN yielded atomic §level information of friction and tribochemical§reactions. Such information can be applied §to design surfaces with tailored frictional§properties and choosing proper materials for§frictional systems.