In this talk, we will present a new form of an orbital-energy dependent regularizer that copes with offending denominators that frequently appear in orbital-optimized second-order Moller-Plesset perturbation theory (OOMP2). The resulting wavefunction method, κ-OOMP2, is a reliable fifth-order scaling method that solves two disturbing features of unregularized OOMP2: the singularity in the energy expression and the disappearance of Coulson-Fischer points. We present preliminary performance assessment of this method based on commonly used benchmark sets. Furthermore, we discuss the application of κ-OOMP2 to biradicaloid in conjunction with Yamaguchi’s approximate spin-projection method, which is not possible with unrestricted MP2 or unregularized OOMP2. If time permits, we will further discuss the use of κ-OOMP2 to identify artificial spin-symmetry breaking in carbon clusters such as C<sub>60</sub>.<br/>

Development of reliable, regularized, orbital-optimized, second-Order Møller–Plesset perturbation theory and its application to biradicaloids and artificial spin-symmetry breaking

2019 Spring National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.