Chemical accuracy from small, system-adapted basis functions

TL;DR

This paper introduces a versatile method for creating system-specific basis functions in quantum chemistry, achieving chemical accuracy with minimal basis functions and demonstrating effectiveness on molecular systems.

Contribution

It combines features from multiple traditional basis approaches to efficiently produce accurate results with few basis functions for quantum chemical calculations.

Findings

Achieves chemical accuracy with only 2-3 basis functions per electron in 1D models.

Reproduces natural orbitals effectively.

Shows promising results for molecular energy curves and atomic chains.

Abstract

We propose a general method for constructing system-dependent basis functions for correlated quantum chemical calculations. Our construction combines features from several traditional approaches: plane waves, localized basis functions, and wavelets. In a one-dimensional mimic of Coulomb systems, it requires only 2-3 basis functions per electron to achieve chemical accuracy, and reproduces the natural orbitals. We illustrate its effectiveness for molecular energy curves and chains of many atoms. We discuss the promise and challenges for realistic quantum chemical calculations.