implementation of rigid body/connectivity constraints

[Tomasz Stawski]

Dear DiffPy users,

We have recently released a Python script which uses DiffPy to refine structure of s negative thermal expansion (NTE) material, zirconium vanadate. It can handle a relatively large cell with 1080 atoms, and in addition it performs:

1. Rigid-body Constraints and Connectivity-based Refinement:
Incorporates physically-informed rigid-body restraints based on well-defined polyhedral connectivity. This includes explicit constraints on bond lengths and angles within ZrO₆ octahedra and VO₄ tetrahedra, ensuring structural parameters remain physically realistic and chemically sensible.
2. Adaptive Space-group Symmetry Switching:
Provides functionality to easily transition between different space-group settings (e.g., from higher symmetry groups such as Pa-3 to lower symmetry groups like P213, P23, and ultimately P1). This capability allows the systematic exploration of potential symmetry-breaking structural distortions or subtle symmetry variations typical of NTE materials.

If you are interested, please have a look here:
https://github.com/BAMresearch/ZrV2O7-PDF-Refinement

with kind regards,

Tomasz

[Simon Billinge]

Thanks for sharing this Tomasz!

Simon Billinge

Professor, 

Department of Applied Physics and Applied Mathematics

Columbia University

On Tue, Mar 25, 2025, 3:24 AM Tomasz Stawski <tomasz....@gmail.com> wrote:

Dear DiffPy users, We have recently released a Python script which uses DiffPy to refine structure of s negative thermal expansion (NTE) material, zirconium vanadate. It can handle a relatively large cell with 1080 atoms, and in addition it

ZjQcmQRYFpfptBannerStart

This Message Is From an External Sender

This message came from outside your organization.

 

ZjQcmQRYFpfptBannerEnd

--
You received this message because you are subscribed to the Google Groups "diffpy-users" group.
To unsubscribe from this group and stop receiving emails from it, send an email to diffpy-users...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/diffpy-users/70599a8a-5de5-4085-888a-27305a39d2f3n%40googlegroups.com.