title: Polynomial scaling approximations and dynamic correlation corrections to doubly occupied configuration interaction wave functions.
abstract: A class of polynomial scaling methods that approximate Doubly Occupied Configuration Interaction (DOCI) wave functions and improve the description of dynamic correlation is introduced. The accuracy of the resulting wave functions is analysed by comparing energies and studying the overlap between the newly developed methods and full configuration interaction wave functions, showing that a low energy does not necessarily entail a good approximation of the exact wave function. Due to the dependence of DOCI wave functions on the single-particle basis chosen, several orbital optimisation algorithms are introduced. An energy-based algorithm using the simulated annealing method is used as a benchmark. As a computationally more affordable alternative, a seniority number minimising algorithm is developed and compared to the energy based one revealing that the seniority minimising orbital set performs well. Given a well-chosen orbital basis, it is shown that the newly developed DOCI based wave functions are especially suitable for the computationally efficient description of static correlation and to lesser extent dynamic correlation.
authors.affiliation: Department of Inorganic and Physical Chemistry, Ghent University, Krijgslaan 281 (S3), 9000 Gent, Belgium.
authors.forename: Mario
authors.initials: M
authors.lastname: Van Raemdonck
authors.affiliation: Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and Instituto de Física de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Universitaria, 1428 Buenos Aires, Argentina.
authors.forename: Diego R
authors.initials: DR
authors.lastname: Alcoba
authors.affiliation: Center for Molecular Modeling, Ghent University, Technologiepark 903, 9052 Zwijnaarde, Belgium.
authors.forename: Ward
authors.initials: W
authors.lastname: Poelmans
authors.affiliation: Department of Inorganic and Physical Chemistry, Ghent University, Krijgslaan 281 (S3), 9000 Gent, Belgium.
authors.forename: Stijn
authors.initials: S
authors.lastname: De Baerdemacker
authors.affiliation: Departamento de Química Física, Facultad de Ciencia y Tecnología, Universidad del País Vasco, Apdo. 644, E-48080 Bilbao, Spain.
authors.forename: Alicia
authors.initials: A
authors.lastname: Torre
authors.affiliation: Departamento de Química Física, Facultad de Ciencia y Tecnología, Universidad del País Vasco, Apdo. 644, E-48080 Bilbao, Spain.
authors.forename: Luis
authors.initials: L
authors.lastname: Lain
authors.affiliation: Departamento de Ciencias Exactas, Ciclo Básico Común, Universidad de Buenos Aires, Ciudad Universitaria, 1428 Buenos Aires, Argentina.
authors.forename: Gustavo E
authors.initials: GE
authors.lastname: Massaccesi
authors.affiliation: Center for Molecular Modeling, Ghent University, Technologiepark 903, 9052 Zwijnaarde, Belgium.
authors.forename: Dimitri
authors.initials: D
authors.lastname: Van Neck
authors.affiliation: Department of Inorganic and Physical Chemistry, Ghent University, Krijgslaan 281 (S3), 9000 Gent, Belgium.
authors.forename: Patrick
authors.initials: P
authors.lastname: Bultinck