Coupled Cluster Degree of the Grassmannian
- Resource Type
- Working Paper
- Authors
- Borovik, Viktoriia; Sturmfels, Bernd; Sverrisdóttir, Svala
- Source
- Subject
- Mathematics - Commutative Algebra
Mathematics - Algebraic Geometry
Mathematics - Combinatorics
Physics - Chemical Physics
- Language
We determine the number of complex solutions to a nonlinear eigenvalue problem on the Grassmannian in its Pl\"ucker embedding. This is motivated by quantum chemistry, where it represents the truncation to single electrons in coupled cluster theory. We prove the formula for the Grassmannian of lines which was conjectured in earlier work with Fabian Faulstich. This rests on the geometry of the graph of a birational parametrization of the Grassmannian. We present a squarefree Gr\"obner basis for this graph, and we develop connections to toric degenerations from representation theory.
Comment: 13 pages