Scientific Computing Research Unit and Department of Chemistry, University of Cape Town, Rondebosch, South Africa.|Department of Computer Science, University of Freiburg, Freiburg, Germany.|Scientific Computing Research Unit and Department of Chemistry, University of Cape Town, Rondebosch, South Africa.|Department of Computer Science, University of Freiburg, Freiburg, Germany.|Scientific Computing Research Unit and Department of Chemistry, University of Cape Town, Rondebosch, South Africa.