# A Density-Based Basis-Set Correction For Wave Function Theory

## TL;DR

This paper introduces a universal, density-based correction for wave function methods that estimates and reduces basis-set incompleteness errors using a spatially adaptive range-separation function, improving energy calculations near the CBS limit.

## Contribution

The paper presents a novel, adaptive density-based basis-set correction method applicable to any wave function approach, eliminating the need for an ad hoc range-separation parameter.

## Key findings

- Achieves near-CBS limit energies for molecules with compact basis sets.
- Works with various wave function methods, including CCSD(T).
- Reduces basis-set incompleteness errors effectively.

## Abstract

We report a universal density-based basis-set incompleteness correction that can be applied to any wave function method. The present correction, which appropriately vanishes in the complete basis set (CBS) limit, relies on short-range correlation density functionals (with multi-determinant reference) from range-separated density-functional theory (RS-DFT) to estimate the basis-set incompleteness error. Contrary to conventional RS-DFT schemes which require an \textit{ad hoc} range-separation \textit{parameter} $\mu$, the key ingredient here is a range-separation \textit{function} $\mu(\bf{r})$ that automatically adapts to the spatial non-homogeneity of the basis-set incompleteness error. As illustrative examples, we show how this density-based correction allows us to obtain CCSD(T) atomization and correlation energies near the CBS limit for the G2 set of molecules with compact Gaussian basis sets.