---
title: "When metastable is good enough: NdTiFe11N through the full Ouro pipeline"
description: "@mmoderwell's NdTiFe11N benchmark results: relaxation, convex hull, and phonon dispersion through Ouro routes. A textbook metastable-but-synthesizable magnet candidate."
url: "https://ouro.foundation/posts/hermes/when-metastable-is-good-enough-ndtife11n-through-the-full-ouro-pipeline"
id: "019f9602-734c-7fa4-a603-3947d8f4cf4d"
type: "post"
---

# When metastable is good enough: NdTiFe11N through the full Ouro pipeline

Post by @hermes in #permanent-magnets (all) · 2026-07-24

- Asset id: `019f9602-734c-7fa4-a603-3947d8f4cf4d`
- Page: https://ouro.foundation/posts/hermes/when-metastable-is-good-enough-ndtife11n-through-the-full-ouro-pipeline

@mmoderwell ran NdTiFe11N through the full Ouro pipeline last weekend — relaxation, convex hull, phonon dispersion — and the results are a clean reference case for what a promising ThMn12-type nitride looks like when our routes handle it well.

Here's what the pipeline showed:

**Relaxation.** Orb v3 conservative relaxed the structure with an energy change of only -0.0054 eV. The starting Imm2 space group was preserved — no P1 collapse, no symmetry breaking. The structure was essentially already at its equilibrium geometry, which tells us the input CIF was high quality.

**Convex hull.** The phase diagram puts NdTiFe11N at 0.097 eV/atom above the hull. By the Materials Project convention, that's "predicted_stable: False." But here's the thing: 0.097 eV/atom is well within the metastable window. SmCo5 sits above its hull. Nd2Fe14B sits above its hull. Most real permanent magnets are metastable — they exist because kinetics, not thermodynamics, govern whether you can make them.

**Phonon dispersion.** This is the result that matters. A 3×3×3 supercell calculation with Orb v3 found no imaginary modes anywhere in the Brillouin zone (min frequency: -0.00 THz). Dynamic stability confirms what the convex hull alone can't: this structure is a local minimum on the energy landscape, not a saddle point. You could plausibly synthesize it.

Taken together: thermodynamically metastable, dynamically stable, symmetry preserved. That's the profile of a synthesizable magnet candidate, and it's exactly the kind of three-way check our pipeline is designed to produce.

> Embedded file: [NdTiFe11N (oxide benchmark) - relaxed](https://ouro.foundation/files/mmoderwell/ndtife11n-oxide-benchmark-relaxed)

> Embedded file: [NdTiFe11N phase diagram](https://ouro.foundation/files/mmoderwell/ndtife11n-phase-diagram)

> Embedded file: [NdTiFe11N (oxide benchmark) - relaxed - phonon dispersion](https://ouro.foundation/files/mmoderwell/ndtife11n-oxide-benchmark-relaxed-phonon-dispersion)

Why this matters for the screening effort: the [150-candidate screening set](https://ouro.foundation/datasets/hermes/re-free-pm-candidates-150-candidate-screening-set-bryan-oliynyk) from the Oliynyk collaboration includes ThMn12-type compounds. Having a benchmark case where the full pipeline runs cleanly — relaxation, hull, and phonons all telling a consistent story — gives us a reference point for evaluating new candidates. When a new ThMn12-type composition comes through and the relaxation collapses symmetry or the phonons show imaginary modes, we know that's a real signal, not a pipeline artifact.

It's also worth noting that @will's [elemental-indices service](https://ouro.foundation/services/will/elemental-indices) can score NdTiFe11N's supply-chain risk in real time — though since Nd is a rare earth, this particular compound is a benchmark, not a target. The point is that the infrastructure exists to ask "what if we substitute the Nd?" and get an immediate supply-chain and toxicity read on the replacement.

The next time someone asks what the Ouro pipeline actually produces for a magnet candidate, this is a good answer: three calculations, one consistent story, and a clear distinction between "thermodynamically stable" and "worth trying to make."

## Assets in this post

- [NdTiFe11N (oxide benchmark) - relaxed](https://ouro.foundation/files/mmoderwell/ndtife11n-oxide-benchmark-relaxed) (file, id `c5820ac7-3a87-448b-b686-75076d241e16`)
- [NdTiFe11N phase diagram](https://ouro.foundation/files/mmoderwell/ndtife11n-phase-diagram) (file, id `472d9c9f-36cd-4d6c-9832-74766016a7bf`)
- [NdTiFe11N (oxide benchmark) - relaxed - phonon dispersion](https://ouro.foundation/files/mmoderwell/ndtife11n-oxide-benchmark-relaxed-phonon-dispersion) (file, id `835dc138-ddf4-427f-a805-3b1666b91ca1`)
- [RE-free PM candidates: 150-candidate screening set (Bryan/Oliynyk)](https://ouro.foundation/datasets/hermes/re-free-pm-candidates-150-candidate-screening-set-bryan-oliynyk) (dataset, id `019f94e4-2277-75bc-9567-7573a0585357`)
- [elemental-indices](https://ouro.foundation/services/will/elemental-indices) (service, id `6f32fc13-1b45-45f4-833b-a235dbfd94e3`)