arXiv subjects

Songge Yang

Publications and source records attributed to Songge Yang.

3 recordsLinked to original sources

arXiv2025

Masgent: An AI-assisted Materials Simulation Agent

Density functional theory (DFT) and machine learning potentials (MLPs) are essential for predicting and understanding materials properties, yet preparing, executing, and analyzing these simulations typically requires extensive scripting, multi-step procedures, and significant high-performance computing (HPC) expertise. These challenges hinder reproducibility and slow down discovery. Here, we introduce Masgent, an AI-assisted materials simulation agent that unifies structure manipulation, automated VASP input generation, DFT workflow construction and analysis, fast MLP-based simulations, and lightweight machine learning (ML) utilities within a single platform. Powered by large language models (LLMs), Masgent enables researchers to perform complex simulation tasks through natural-language interaction, eliminating most manual scripting and reducing setup time from hours to seconds. By standardizing protocols and integrating advanced simulation and data-driven tools, Masgent lowers the barrier to performing state-of-the-art computational methodologies, enabling faster hypothesis testing, pre-screening, and exploratory research for both new and experienced practitioners.

physics.comp-ph↗

arXiv2023

Ab initio Investigations on the Electronic Properties and Stability of Cu-Substituted Lead Apatite (LK-99) family with different doping concentrations (x=0, 1, 2)

The pursuit of room-temperature ambient-pressure superconductivity in novel materials has sparked interest, with recent reports suggesting such properties in Cu-substituted lead apatite, known as LK-99. However, these claims lack comprehensive experimental and theoretical support. In this study, we address this gap by conducting ab initio calculations to explore the impact of varying doping concentrations (x = 0, 1, 2) on the stability and electronic properties of five compounds in the LK-99 family. Our investigations confirm the isolated flat bands that intersect the Fermi level in LK-99 (Pb9Cu(PO4)6O:Cu ). In contrast, the other four parent compounds exhibit insulating behavior with wide band gaps. X-ray diffraction spectra based on the DFT simulations at 0K confirm the presence of Cu substitution on Pb(1) sites in the originally synthesized LK-99 sample, while an extra peak suggests potential alternative like Pb8Cu2(PO4)6 phases due to compositional variations in the original LK-99 samples. Furthermore, the LK-99 structure undergoes substantial lattice constriction, resulting in a significant 5.5% reduction in volume and 6.8% in area of two mutually inverted triangles formed by Pb(2) atoms. Meanwhile, energy calculations reveal a marginal energy preference for substituting Cu on Pb(2) sites over Pb(1) sites, with a difference of approximately 0.010 eV per atom (roughly 0.9645 k/mol). Intriguingly, at pressures exceeding 73 GPa, stability shifts towards LK-99 containing Cu substitutions on Pb(1) sites. Despite exhibiting higher electronic conductivity than parent compounds, Pb9Cu(PO4)6O:Cu falls short of the conductivity levels observed in metals or advanced oxide conductors with the simulation based on the Boltzmann transport theory.

cond-mat.mtrl-sci↗

arXiv2021

Ab initio simulations on the pure Cr lattice stability at 0K: Verification with the Fe-Cr and Ni-Cr binary systems

Significant discrepancies have been observed and discussed on the lattice stability of Cr between the predictions from the ab initio calculations and the CALPHAD approach. In the current work, we carefully examined the possible structures for pure Cr and reviewed the history back from how Kaufman originally determined the Gibbs energy of FCC-Cr in the 1970s. The reliability of Cr lattice stability derived by the CALPHAD and ab initio approaches was systematically discussed. It is concluded that the Cr lattice stability based on the CALPHAD approach has large uncertainty. Meanwhile, we cannot claim that the ab initio HFCC-Cr is error-free as FCC-Cr is an unstable phase under ambient conditions. The present work shows that the ab initio HFCC-Cr can be a viable scientific approach. As both approaches have their limitations, the present work propose to integrate the ab initio results into the CALPHAD platform for the development of the next generation CALPHAD database. The Fe-Cr and Ni-Cr binary systems were chosen as two case studies demonstrating the capability to adopt the ab initio Cr lattice stability directly into the current CALPHAD database framework.

cond-mat.mtrl-sci↗