The Influence of Orbital Rotation on the Energy of Closed-Shell Wavefunctions Peter A. Limacher a , Taewon D. Kim a , Paul W. Ayers a* , Paul A. Johnson a , Stijn De Baerdemacker b , Dimitri Van Neck b , Patrick Bultinck c a Department of Chemistry and Chemical Biology McMaster University Hamilton, Ontario L8S 4M1 Canada b Center for Molecular Modelling Ghent University 9052 Zwijnaarde Belgium c Department of Inorganic and Physical Chemistry Ghent University 9000 Gent Belgium Keywords: doubly-occupied configuration interaction, orbital optimization, closed-shell wavefunc- tion, static electron correlation December 3, 2013 1