<b>MOSP: A User-interface Package</b><b> </b><b>for Simulating Metal Nanoparticle’s Structure and Reactivity under Operando Conditions</b>

Structures of metal nanoparticles (NPs) significantly influence their catalytic reactivities. Recent <i>in situ</i> experimental observations of dramatic structural changes in NPs underscore the need to establish a dynamic structure-property relationship that accounts for the reconstruction of NPs in reactive environments. Here, we present the MOSP, a free and open-source graphical user interface (GUI) package designed to simulate the structure and reactivity of metal NPs under operando conditions. MOSP integrates two models: the multiscale structure reconstruction (MSR) model predicting equilibrium metal NP structures under specific reaction conditions and the kinetic Monte Carlo (kMC) model simulating the reaction dynamics. This combination allows for the exploration of the dynamic structure-property relationships of NPs. MOSP enhances user accessibility through its intuitive GUI, facilitating easy input, post-processing, and visualization of simulation data. This article is the release note of MOSP, focusing on its implementation and functionality.