• Pyrazine excited states revisited using the extended multi-state complete active space second-order perturbation method 

      Shiozaki, Toru; Woywod, Clemens Joachim; Werner, Hans-Joachim (Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
      We demonstrate that the recently developed extended multi-state complete active space second-order perturbation theory (XMS-CASPT2) [Shiozaki et al., J. Chem. Phys., 2011, 135, 081106] provides qualitatively correct potential energy surfaces for low-lying excited singlet states of pyrazine, while the potential energy surfaces of the standard MS-CASPT2 methods are ill-behaved near the crossing ...