When the electrons of atoms and molecules are excited, they temporarily enter an energised state. This electronic excitation occurs during biological processes such as photosynthesis and vision (light forming an image on the eye's retina). Unfortunately, the current methods used to calculate excitation energies are not always ideally suited to studying large and complex biological molecules. These methods may be either highly accurate but expensive and complex, or cheap but less accurate and applicable only to simple, small molecules. The EU-funded 'Wave-function theory embedded in density-functional theory with coupled excitations' (WFTINDFTCE) project developed equations for an accurate yet cost-effective new method. With complex computing, researchers tested how well these equations could calculate the excitation energy of larger biological molecules. Among the investigated applications were small compounds such as a water–ammonia complex, as well as the DNA base pair made up of guanine and cytosine. The novel method is expected to have several theoretical applications in computer programmes and in the study of general molecular properties. It will allow for the interpretation of complex experimental data and could even assist in designing new materials.
Computational chemistry, electronic properties, biological molecules, electronic excitation, biological processes, excitation energies, wave-function theory, density-functional theory, coupled excitations, excitation energy, molecular properties