Harrison has authored or co-authored a wide range of articles 
Harrison's research career started with his PhD, which was concerned with developing a quantitative and 
predictive theory of the electronic states in substitutionally disordered systems.
Harrison has furthered the practical use of quantum theory for predictive calculations in materials discovery and
optimisation. He has developed methods for robust and efficient calculations on functional materials in
which strong electronic interactions are dominant and used them to study processes in previously poorly
understood materials such as transition metal oxides,
oxide interfaces,
and functional materials
In doing so he has made significant contributions to the understanding of catalysis and photocatalysis at surfaces,
the stability of polar surfaces, spin dependent transport in low dimensional systems, high temperature
magnetism in organic and metal-organic materials and the thermodynamics of energy storage materials
The techniques he has developed have consistently extended the state of the art and are now used world-wide in both
academic and commercial research programmes.