Data from: First-principles investigation of surface mechanochemistry of transition metal phosphides under oxygen and benzene atmospheres

Sensoy, Mehmet Gokhan 1 2 ; Qin, Shihan1; Jiang, Zhen1; de Boer, Maarten3; Carpick, Robert1; Rappe, Andrew1

Published Jan 02, 2026 on Dryad. https://doi.org/10.5061/dryad.q83bk3jx2

Data files

Jan 02, 2026 version files 1.88 GB

2025_04_03_TMPs_under_O_and_bz_atm_Dryad.zip

1.88 GB
README.md

6.36 KB

Abstract

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.

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
Corresponding Author: Andrew M. Rappe (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, Ru₂P, Rh₂P, 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--<# of adsorbed |oxygen>.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.<#######>, err.<#######>, 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:

Data was derived from the following sources: