Internally contracted multiconfiguration-reference configuration interaction calculations for excited states

  title={Internally contracted multiconfiguration-reference configuration interaction calculations for excited states},
  author={Peter J. Knowles and Hans-Joachim Werner},
  journal={Theoretica chimica acta},
SummaryThe calculation of electronically excited states with the internally contracted multiconfiguration-reference configuration interaction (CMRCI) method is discussed. A straightforward method, in which contracted functions for all states are included in the basis, is shown to be very accurate and stable even in cases of narrow avoided crossings. However, the expense strongly increases with the number of states. A new method is proposed, which employs different contracted basis sets for each… Expand
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