English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We describe a formulation of multi-reference perturbation theory that obtainsa rigorous upper bound to the second order energy by minimizing the Hylleraasfunctional in the space of matrix product states (MPS). The first orderwavefunctions so obtained can also be used to compute the third order energywith little overhead. Our formulation has several advantages including (i)flexibility with respect to the choice of zeroth order Hamiltonian, (ii)recovery of the exact uncontracted multi-reference perturbation theory energiesin the limit of large MPS bond dimension, (iii) no requirement to compute highbody density matrices, (iv) an embarrassingly parallel algorithm (scaling up tothe number of virtual orbitals, squared, processors). Preliminary numericalexamples show that the MPS bond dimension required for accurate first orderwavefunctions scales sub-linearly with the size of the basis.

A flexible multi-reference perturbation theory by minimizing the Hylleraas functional with matrix product states