text: Following the retirement in 2007 from Hannover professorship, Werner Urland resumed the scientific activity as guest senior researcher in the group of Professor Claude Daul at University of Fribourg (Switzerland), where he proposed a topic related to the so-called "Warm-White Light", namely the improvement of blue-type Light-emitting diodes (LEDs) towards the better resemblance to the sunlight spectrum by coating with appropriate phosphors based on lanthanide doped materials.  The topic represents a hot relevance in the context of the trends of eliminating traditional incandescent light bulbs, for the sake of energy saving new technologies . This technological challenge is underlined by the award of the 2014 Nobel Prize in Physics "for the invention of efficient blue light-emitting diodes, which has enabled bright and energy-saving white light sources" to Shuji Nakamura, Isamu Akasaki and Hiroshi Amano and by the declaration of 2015 as International Year of Light and Light-based Technologies, (IYL 2015). 
  Hybridizing Werner's Urland expertise in experimental and theoretical aspects of rare earth materials with a computation and analysis methodology due to C. Daul and M. Atanasov, altogether with methodological knowledge of external collaborators of the group, a series of works was produced, dealing with the analysis and prediction form first principles of the key factors in the luminescence of relevant lanthanide ions in various environments.
  The modelling is based on a set of algorithmic steps abbreviated as LFDFT,  consisting in non-routine calculations in the frame of Density Functional Theory (DFT) followed by the analysis in the frame of Ligand Field Theory. The issue of first principles calculations on rare-earth systems is non-trivial, because of special features of the f-shell, such as the shielded and weakly interacting nature, that poses technical and conceptual difficulties, in relation to modern methods of quantum chemistry. The specific problem of the modelling the luminescence of rare-earth systems called the need of extending the ligand field phenomenology, from its one-shell status (dedicated to d or f electrons) to a two-shell Hamiltonian (quantum mechanics), comprising simultaneously the d and f shells, because the involved optical transitions  have inter-shell nature. 
  Also recently, Werner Urland, entered the terrain of actinide chemistry, explaining intriguing magnetic behaviour due strong ligand field on uranium(IV) ions in thiophosphates and silicates.
  The whole deal underlines the validity and renewed value of Werner Urland's early ideas about the theoretical and practical aspects emerging from the chemistry and physics of f-elements.