Calculation of Surface Free Energy of Atomic and Molecular Systems 

CCP5-CECAM sandpit

Nicodemo Di Pasquale^a, Lorenzo Rovigatti^b 

^aBrunel University London, London, UK (current affiliation: University of Bologna, Bologna, Italy) ^bLa Sapienza University, Rome, Italy 

The project is framed within the long-standing interest in understanding interfacial properties, which are central to many natural phenomena and technological applications, including pharmaceuticals, biological systems, and advanced optical and colloidal materials, and particularly the Surface Free Energy (SFE) which represents a key thermodynamic quantity for the stability and formation of interfaces. While Molecular Dynamics (MD) simulations offer a powerful microscopic approach for its determination, reliable and standardized methods for computing surface free energy are still largely limited to simple inorganic systems. This observation motivates the necessity of coordinated efforts to consolidate methodologies and tools for studying interfaces in complex materials. 

The aim of this project was two-fold: i) to bring together research groups addressing the determination of surface properties from complementary theoretical, methodological, and application-oriented perspectives, ii) to disseminate the technical and methodological expertise required to carry out such calculations. The tangible outcomes of the project consist of a series of activities established to foster collaboration, including academic visits and workshops, as well as dedicated training courses. In addition, the project resulted in peer-reviewed publications, comprising a broad, multi-author review in a high impact journal of methodologies for calculating surface free energy using Molecular Dynamics simulations and two software-focused papers aimed at disseminating the associated computational tools.  

A more detailed summary of the activities and outputs is given. 

Summary of the activities performed during the project: 

• Online lectures given at MMM Hub Software Spotlight (19 January 2023): https://thomasyoungcentre.org/event/mmm-hub-software-spotlight-lammps/ 

• 8-hour course for PhD students at Politecnico di Torino, Italy “Molecular Dynamics modelling with LAMMPS” 

• 1 week academic visiting (May 2023) of Di Pasquale Nicodemo and Ruslan Davidchack at Universidad Complutense de Madrid, (Madrid, Spain) hosted by Prof. Carlos Vega and Dr Jorge Espinosa 

• 2 workshops in Brunel attended by 10 people from different part of Europe and US (2^nd – 3^rd March 2023 and 3^rd – 5^th September 2023) 

Summary of the output produced: 

• Andres R Tejedor, Ignacio Sanchez-Burgos, Eduardo Sanz, Carlos Vega, Felipe J Blas, Ruslan L Davidchack, Nicodemo Di Pasquale, Jorge Ramirez, Jorge R Espinosa. (2024). Mold: a LAMMPS package to compute interfacial free energies and nucleation rates. Journal of Open Source Software, 9(95), 6083. 

• Nicodemo Di Pasquale, Ruslan Davidchack, & Lorenzo Rovigatti, L. (2024). CLEAVING: a LAMMPS package to compute surface free energies. Journal of Open Source Software, 9(94), 5886. 

• Nicodemo Di Pasquale, Jesús Algaba, Pablo Montero de Hijes, Ignacio Sanchez-Burgos, Andres R Tejedor, Stephen R Yeandel, Felipe J Blas, Ruslan L Davidchack, Jorge R Espinosa, Colin L Freeman, John H Harding, Brian B Laird, Eduardo Sanz, Carlos Vega, Lorenzo Rovigatti (2025). Solid–liquid interfacial free energy from computer simulations: challenges and recent advances. Chemical Reviews, 125(10), 5003-5053.