Theoretical modeling of edge-controlled growth kinetics and structural engineering of 2D-MoSe2
Scope
First ReaxFF description for Mo/Se/H trained on first-principles data for 2D MoSe\(_2\), used for MD and a Wulff-based model of edge-limited growth morphology.
Summary¶
The article presents a ReaxFF parameterization for Mo/Se/H intended for large-scale reactive molecular dynamics of 2D MoSe\(_2\) synthesis and processing. Training draws primarily on first-principles energetics for periodic and non-periodic systems. The fitted potential is used to describe the metallic–semiconducting structural transition, defect energetics, and selenium-vacancy migration, and—together with a Wulff-construction-based model—to interpret morphology evolution of MoSe\(_2\) domains during growth. Edge formation energies of MoSe\(_2\) nanoribbons with different Se coverages are included in the training to support simulation of edge-mediated growth kinetics.
MoSe\(_2\) growth is edge-limited in many CVD conditions; embedding edge energetics directly in the reactive FF training set distinguishes this work from bulk-only fits.
Methods¶
Force-field training (ReaxFF for Mo/Se/H). A ReaxFF set is fitted to DFT energies and structures for bulk and few-layer MoSe\(_2\), nanoribbon edge terminations with varied Se coverage, and defect motifs relevant to edge-limited CVD kinetics (formation energies, barriers, and Wulff inputs). Functional, basis, k-mesh, and the ReaxFF Monte Carlo / optimizer workflow are given in Mater. Sci. Eng. B and the SI; the same lineage appears in other van Duin-group ReaxFF papers cited there. Training benchmarks the metallic↔semiconducting bistability and Se-vacancy migration trends advertised in the abstract.
MD application (LAMMPS with the new ReaxFF). Molecular dynamics with the fitted ReaxFF in LAMMPS (velocity Verlet-style integration as in Section 2) samples edge and vacancy dynamics in NVT PBC supercells; time step (fs), ps–ns duration, and Nosé–Hoover-class thermostat settings for setpoint temperatures in K are tabulated in the MSE B article and SI. NPT barostat — N/A in the highlighted NVT defect blocks unless the VOR adds a stress-relaxation case. Hydrostatic pressure (bar) — N/A in those NVT blocks. External E-field, shear, metadynamics — N/A for the cases in the abstract-level summary.
Continuum / Wulff coupling (not stand-alone MD). ReaxFF edge excess energies feed a Wulff-type model (with the L.-Q. Chen-group nucleation/continuum coupling as stated) to relate anisotropic edge stiffnesses to CVD island morphology.
Findings¶
Outcomes and mechanisms. The fitted ReaxFF recovers the metallic/semiconducting bistability, the defect energetics highlighted in the abstract, and the Se-vacancy migration trends used to interpret CVD kinetics. Wulff-based analysis connects anisotropic ReaxFF edge energies to triangular vs hexagonal island shapes and to shifts with Se chemical potential-like process variables in the model.
Comparisons. The article relates these predictions to CVD MoSe\(_2\) morphology data and to prior DFT kinetic work as cited; figure-level numbers belong in the VOR PDF.
Sensitivity and levers. Edge Se coverage and the chemical potential inputs to the Wulff construction move predicted island habits; MD at different T changes which defect pathways are kinetically sampled.
Corpus honesty. This wiki page is a curated summary; for Wulff inputs, k-meshes, and run parameters, use pdf_path and the SI tied to the VOR DOI — not a substitute for the manuscript tables.
Limitations¶
Scope is limited to the chemistry and geometries covered by the training set and the growth models discussed in the paper.
Relevance to group¶
Group-authored ReaxFF development for selenide TMDs with explicit edge energetics for growth phenomenology.