Approach IV: fitting with additional Br data

Constrained fit to initial values with additional Br data

👀 Overview

Summary	This fit adds additional Br ESP data following a hypothesis that a lack of Br data was responsible for the poor performance of Br compounds in condensed phase properties. Performance unfortunately did not improve. While working on this approach, it became apparent that we weren’t sure where the initial values for each virtual site came from – while they had seemed to come from Qubekit, we could not reproduce them in Qubekit. In Approach V we took a step back and restarted the project from Qubekit initial values, as well as exploring other directions.
GitHub repo/branch
Status	WON'T PROGRESS

Stage	Milestone/Benchmark	Contributors	Deadline	Status
Train virtual sites and BCCs to existing HF/6-31G* data and additional Br data, with a weak constraint to initial charge	Compute additional multi-Br data	Lily Wang	Nov 2023	COMPLETED
	Re-fit 2.1.0 BCCs to ESP data	Lily Wang	Dec 2023	COMPLETED
Re-fit valence and vdW parameters to condensed phase properties	Re-fit FF terms for vsites-candidate	Lily Wang	Mar 2024	COMPLETED
Benchmark	Improved or equivalent performance for molecules with virtual sites added (Cl, Br, pyridines) on training data		Mar 2024	FAILED