Overview
Constrained fit to initial values. |
OverviewSummary | In Approach II, the virtual site charge ~0.17e on the pyridine was regarded as somewhat low. This fit adds a weak charge restraint to initial values for all virtual sites, which primarily affected the pyridine virtual site. The resulting charge around 0.3 e did not improve performance on condensed phase properties. In addition, we took a closer look at Br properties, which also showed worse performance. This may be due to a lack of multi-site Br fitting data. In Approach IV we attempted a re-fit with additional data. |
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GitHub repo/branch | |
Status |
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Milestones and metricsOutside of technical issues, milestones and deliverables should not be revisited once marked as completed. If at any point the project fails to pass a required metric and the driver and approver both decide to re-start the project from an earlier point in the workflow, a new project approach plan should be created.
Stage | Milestone/Benchmark | Contributors | Deadline | Status |
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Train virtual sites and BCCs to existing HF/6-31G* data, with a weak constraint to initial charge | Re-fit 2.1.0 BCCs and virtual sites to ESP data | Oct 2023 | ||
Re-fit valence and vdW parameters to condensed phase properties | Re-fit FF terms for vsites-candidate | Dec 2023 |
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Benchmark | Improved or equivalent performance for molecules with virtual sites added (Cl, Br, pyridines) on training data | Dec 2023 *Note: this was delayed due to an unexpected outage with lilac access. | Presentation: https://docs.google.com/presentation/d/1fQjJn2OfApAmxfSCdxxwPuGveWoS0gPRYZ9MVL32OVk/edit#slide=id.g2a39d07bb62_0_21 |
Progress and findingsThe pyridine virtual site stabilized around 0.3 e:
No real effect was observed on the halogens with the restraint:
This change in pyridine charges didn’t appear to substantially affect the condensed phase properties.
