['Theoretical', 'studies', 'play', 'a', 'critical', 'role', 'in', 'these', 'studies', ',', 'since', 'the', 'analysis', 'of', 'the', 'experimental', 'data', 'requires', 'calculations', 'to', 'provide', 'a', 'link', 'between', 'the', 'observed', 'spectral', 'features', 'and', 'the', 'underlying', 'structure', '.']