DOI: 10.5061/dryad.q83bk3jx2
title: Data from: First-principles investigation of surface mechanochemistry of transition metal phosphides under oxygen and benzene atmospheres

description: Transition metal phosphides (TMPs) have aroused widespread research
 interest in the past decade due to their excellent electrical and
 mechanical properties. Nonetheless, their application in micro- and
 nanoelectromechanical systems (MEMS and NEMS) has not been investigated.
 Here, we use density functional theory (DFT) to explore the potential of
 four transition-metal phosphides to act as contact materials of MEMS/NEMS
 switches. Specifically, we first investigate the thermodynamic stability
 of Ru2P, RuP, Rh2P, and TiP under an oxygen environment. Then, using
 benzene as the background gas, the mechanical contact cycle is modeled to
 examine the process of tribopolymer formation on the surface of the
 contacts, which has been reported as the major reason for conductance loss
 after repeated actuation. The results show that Ru2P and Rh2P are
 excellent choices for avoiding friction-induced polymerization, making
 them promising contact materials for MEMS/NEMS switches.
description: # Data from: First-principles investigation of surface mechanochemistry of
 transition metal phosphides under oxygen and benzene atmospheres
 **Authors:** Mehmet Gokhan Sensoy, Shihan Qin, Zhen Jiang, Maarten P. de
 Boer, Robert W. Carpick, Andrew M. Rappe **Journal:** ACS Applied
 Materials & Interfaces\ **DOI:**
 [https://doi.org/10.1021/acsami.5c00370](https://doi.org/10.1021/acsami.5c00370) **Corresponding Author:** Andrew M. Rappe ([rappe@sas.upenn.edu](mailto:rappe@sas.upenn.edu))\ **Publication Date:** 2025 ## Overview This repository contains the complete set of computational data supporting the findings of the above-referenced publication. The research uses Density Functional Theory (DFT) to investigate four transition-metal phosphides (RuP, Ru~2~P, Rh~2~P, and TiP) as potential contact materials for micro- and nanoelectromechanical systems (MEMS/NEMS) switches. The dataset systematically explores their surface oxidation thermodynamics and resistance to friction-induced polymerization (tribopolymer formation) under benzene atmosphere during simulated mechanical contact cycles. \**Please see our manuscript for details. ## Directory Structure 2025_04_03_TMPs_under_O_and_bz_atm_Dryad.zip/ \|-- RuP_Ru2P_Rh2P_TiP_phosphides_bulk_phase_stability.zip \| |--Rh2P/ \| |--RuxPy/ \| |--TiP/ \| *Description: Each directory includes bulk structure files with .vasp extension.* \|-- RuP_Ru2P_Rh2P_TiP_phosphides_surface_slabs_stability.zip \| |--RuP/ \| |-- Ru2P/ \| |-- Rh2P/ \| |-- TiP/ \| *Description: Each directory includes surface slabs cleaved by the bulk-crsytal sturctures.* \|-- RuP_Rh2P_TiP_phosphides_surface_search_gcmc_simulations.zip \| |-- RuP.zip/mu_P* \| |-- Ru2P.zip/mu_P \| |-- Rh2P.zip/mu_P \| |-- TiP.zip/mu_P \| *Description: Each directory includes separated ai-gcmc simulations directories for different chemical potential of phosphorus. The files generated by ab initio grand canonical Monte Carlo simulations. Please see our manuscript for details.* \|-- RuP_Ru2P_Rh2P_TiP_phosphides_surfaces_gcmc_oxidation_simulations.zip \| |-- RuP.zip/mu_O* \| |-- Ru2P.zip/mu_O \| |-- Rh2P.zip/mu_O* \| |-- TiP.zip/mu_O* \| *Description: Each directory includes separated ai-gcmc simulations directories for different chemical potential of oxygen. The files generated by ab initio grand canonical Monte Carlo simulations. Please see our manuscript for details.* \|-- RuP_Ru2P_Rh2P_TiP_phosphides_surface_interaction_energy_simulations.zip \| |-- RuP/ \| |-- |--pristine.zip \| |-- |--oxidized.zip \| |-- Ru2P/ \| |-- |--pristine.zip \| |-- |--oxidized.zip \| |-- Rh2P/ \| |-- |--pristine.zip \| |-- |--oxidized.zip \| |-- TiP/ \| |-- |--pristine.zip \| |-- |--oxidized.zip \| *Description: Each directory includes interaction energy simulations for pristine and oxidized phosphide slabs with different separation distances, i.e., 2A, 2_2A, ... . For some phosphides, the 180 degree rotation was considered, and the files are given under the name of "rotated-180" directory. Please see our manuscript for details.* \|-- Ru2P_Rh2P_phosphides_cycling_simulations.zip \| |-- Rh2P/ \| |-- |-- pristine.zip \| |-- |-- |--compression \| |-- |-- |--expansion \| |-- |-- oxidized.zip \| |-- |-- |--compression \| |-- |-- |--expansion \| |-- Ru2P/ \| |-- |-- pristine.zip \| |-- |-- |--compression \| |-- |-- |--expansion \| |-- |-- oxidized.zip \| |-- |-- |--compression \| |-- |-- |--expansion \| *Description: Contains the core results modeling the mechanical contact cycling simulation files. The numbered subfolders (e.g., 1/, 2/, 3/) within the pristine/ and oxidized/ directories represent sequential steps in the compression and expansion of the simulation system. The number indicates the reduced distance in Angstrom along the c*-axis, which is perpendicular to the material surface. Compression: Starting from the relaxed structure (0/), the c-axis is incrementally reduced (e.g., 1/, 2/, ...), simulating the switch contacts being pressed together. Expansion: Starting from the maximally compressed structure (i.e., 9/), the reduction is incrementally reversed (e.g., 8/, 7/, ... back to 0/), simulating the contacts separating. Please see our manuscript for details. \|-- RuP_Ru2P_Rh2P_TiP_phosphides_benzene_molecule_adsorption_structures.zip \| |-- RuP/CONTCAR*.vasp \| |-- Ru2P/CONTCAR.vasp \| |-- Rh2P/CONTCAR.vasp \| |-- TiP/CONTCAR.vasp \| *Description: Contains the most stable adsorption |configurations (CONTCAR-*-&lt;# of adsorbed |oxygen&gt;.vasp ) for the benzene molecules. ## Vasp output files CHG, CHGCAR, CONTCAR, DOSCAR, EIGENVAL, IBZKPT, INCAR, KPOINTS, OSZICAR, OUTCAR, PCDAT, POSCAR, POTCAR, REPORT, vasp.out, vasprun.xml, WAVECAR, XDATCAR ## Secondary/System Files (can be ignored): Files matching patterns like out.&lt;#######&gt;, err.&lt;#######&gt;, job.slurm, or similar are standard output and error logs automatically generated by the High-Performance Computing (HPC) cluster's job scheduler (e.g., SLURM). They contain technical metadata about the job's runtime, node allocation, and system messages, but do not contain scientific results relevant to the simulation. Users can safely ignore these files for data analysis purposes. ## Code/Softwares Simulation Software: Density Functional Theory calculations were performed using the VASP (Vienna Ab initio Simulation Package). VASP5 is required to reproduce results. ## Visualization/Analysis Atomic structures (POSCAR and CONTCAR files) can be viewed with VESTA. Other outputs are opened by text editors you like. Processed data analysis can be reproduced using Python with libraries like NumPy, Pandas, and Matplotlib. Any python version can be used to reproduce results. ## How to reuse 1\) Install packages pip install ase pip install py4vasp module load vasp/5.4.2 2\) Visualization POSCAR and CONTCAR simulation files (in VASP) can be directly opened by VESTA software. axsf files includes the results of GCMC simulations and can visualized by OVITO software. To analyze individual frames or extract coordinates, users can employ their own scripts (e.g., in Python) or import the file into VESTA. ## Access information Other publicly accessible locations of the data: * n/a Data was derived from the following sources: * n/a