Recent advances in molecular simulation

There have been tremendous advances in Molecular Simulation in recent years, following the implementation of machine learning approaches and data science techniques, the improvement of ab initio methods and the development of advanced sampling techniques. This, in turn, has allowed to accelerate the discovery of new materials for a wide range of applications. Such topics, among others, were discussed at the 2018 AIChE (American Institute of Chemical Engineers) Annual Meeting in Pittsburgh, PA. This special issue of Molecular Simulation is a selection of fourteen papers presented during the meeting, and discussing cutting-edge advances in the field.

The first part of the special issue focuses on the molecular simulation of adsorption processes. N. Scott Bobbitt and Randall Q. Snurr explain that nanoporous materials have, for instance, the potential to store hydrogen at high density and thus provide a storage solution for electric vehicles. Furthermore, they show how a molecular modelling and machine learning approach can screen metal-organic frameworks (MOFs) for hydrogen storage in a high-throughput way. Arni Sturluson, Melanie Huynh, Alec R. Kaija, Caleb Laird, Sunghyun Yoon, Feier Hou, Zhenxing Feng, Christopher E. Wilmer, Yamil J. Colon, Yongchul G. Chung, Daniel W. Siderius and Cory M. Simon review how molecular models and simulations of gas adsorption in MOFs have impacted the discovery of MOFs for a wide range of applications, including e.g. methane and hydrogen storage, carbon dioxide capture and xylene enrichment. They also discuss how large, open databases of MOF crystal structures, post-processed for molecular simulations, are a platform for computational materials discovery. Eun Hyun Cho, Qiang Lyu and Li-Chiang Lin focus on applications of nonporous materials for gas separations. In particular, they show how computational studies conducted for large-scale materials screenings can lead to the discovery of novel membranes for water filtration. Ravi C. Dutta and Suresh K. Bhatia identify the critical role played by interfacial barriers for the design of efficient next generation membranes. They discuss state-of-the-art simulation techniques for determining the nature and significance of interfacial barriers to the fluid transport in nanoporous materials. Ojus Mohana, Quang Thang Trinhb, Arghya Banerjeec and Samir H. Mushrif perform predictions of CO₂ adsorption and reactivity on transition metal surfaces using density functional theory (DFT) methods. They focus on CO₂ conversion reactions on Ni (110) and examine the role of CO as a possible intermediate through a comparison of the calculated binding energies with experimental data.

The second part of the special issue discusses recent applications of molecular simulation to new types of materials. Dimitrios Maroudas, Andre R. Muniz and Ashwin Ramasubramaniam show how atomic-scale modelling can shed light on the structure–properties relations in graphene derivatives and metamaterials. In particular, on the basis of recent molecular dynamics simulations and DFT calculations, they introduce structure–properties relations for a number of two-dimensional materials, including graphene nanomeshes, electron-irradiated graphene and interlayer-bonded twisted bilayer graphene. Evan Pretti, Runfang Mao and Jeetain Mittal focus on the modelling and simulation of DNA-mediated self-assembly for superlattice design. Specifically, they examine how colloidal particles functionalised with DNA impact their interactions with each other, and ultimately how these interactions determine what structures can be obtained from self-assembly. Qing Shao introduces a computational avenue towards the design of zwitterionic anti-biofouling materials. Moreover, Qing Shao discusses how simulations can shed light on a number of properties of these systems, including the role of hydration in their performance, their structure–properties–performance relationships and the development of computational approaches to identify zwitterionic anti-biofouling molecules. Amulya K. Pervaje, Christopher C. Walker and Erik E. Santiso focus on polymeric systems and review the group contribution Statistical Associating Fluid Theory with Mie interaction potentials (SAFT-γ Mie) method for building coarse-grained models of complex molecules. In particular, they show how the corresponding-states SAFT-γ approach can build models useful for high-throughput computational screening of polymeric materials. Li Xi examines how molecular simulation methods can predict the rheological properties of polymer and discusses the integration of molecular simulation with rheological models. Furthermore, Li Xi shows that the recent development of several multiscale frameworks successfully predicts the rheological properties for polymers of experimentally relevant molecular weights.

The third part of the special issue highlights several recent developments in molecular simulation methods. Karthik Ganeshan, Md. Jamil Hossain Adri C. T. van Duin introduce a multiply accelerated ReaxFF molecular dynamics by coupling parallel replica dynamics with collective variable hyperdynamics. They apply this new approach to the pyrolysis of n-dodecane and to the simulation of the ethylene-carbonate/Li system. Sanjib Paul, Nisanth N. Nair, and Harish Vashisth focus on the study of rare events via molecular simulation methods. In particular, they examine both phase space methods, based on transition path sampling, and collective variable methods, including metadynamics and temperature-accelerated sliced sampling. Dilnoza Amirkulova and Andrew D. White discuss how experimental data can be incorporated into molecular simulations through maximum entropy methods. They also review recent applications of experiment directed simulations to ab initio simulations of water and to biological systems. Methary Jaipal and Abhijit Chatterjee introduce a molecular dynamics-based rare-event acceleration technique known as Temperature Programmed Molecular Dynamics. In particular, they show how this method is especially effective for thermally-activated rare events on corrugated energy landscapes.

I would like to thank the reviewers for their invaluable contribution. I would also like to thank Nick Quirke, Editor-In-Chief of Molecular Simulation, and Irene Legaspi, Production Editor, for helping us prepare this special issue.