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Parallel Implementation of Nonadditive Gaussian Process Potentials for Monte Carlo Simulations (2023)
Journal Article
Broad, J., Wheatley, R. J., & Graham, R. S. (2023). Parallel Implementation of Nonadditive Gaussian Process Potentials for Monte Carlo Simulations. Journal of Chemical Theory and Computation, 19(13), 4322-4333. https://doi.org/10.1021/acs.jctc.3c00113

A strategy is presented to implement Gaussian process potentials in molecular simulations through parallel programming. Attention is focused on the three-body nonadditive energy, though all algorithms extend straightforwardly to the additive energy.... Read More about Parallel Implementation of Nonadditive Gaussian Process Potentials for Monte Carlo Simulations.

Machine learning for non-additive intermolecular potentials: quantum chemistry to first-principles predictions (2022)
Journal Article
Graham, R. S., & Wheatley, R. J. (2022). Machine learning for non-additive intermolecular potentials: quantum chemistry to first-principles predictions. Chemical Communications, 58(49), 6898-6901. https://doi.org/10.1039/d2cc01820a

Prediction of thermophysical properties from molecular principles requires accurate potential energy surfaces (PES). We present a widely-applicable method to produce first-principles PES from quantum chemistry calculations. Our approach accurately in... Read More about Machine learning for non-additive intermolecular potentials: quantum chemistry to first-principles predictions.

Gaussian Process Models of Potential Energy Surfaces with Boundary Optimisation (2021)
Journal Article
Broad, J., Preston, S., Wheatley, R. J., & Graham, R. S. (2021). Gaussian Process Models of Potential Energy Surfaces with Boundary Optimisation. Journal of Chemical Physics, 155(14), Article 144106. https://doi.org/10.1063/5.0063534

A strategy is outlined to reduce the number of training points required to model intermolecular potentials using Gaussian processes, without reducing accuracy. An asymptotic function is used at long range and the cross-over distance between this mode... Read More about Gaussian Process Models of Potential Energy Surfaces with Boundary Optimisation.

Gaussian process models of potential energy surfaces with boundary optimization (2021)
Journal Article
Broad, J., Preston, S., Wheatley, R. J., & Graham, R. S. (2021). Gaussian process models of potential energy surfaces with boundary optimization. Journal of Chemical Physics, 155(14), Article 144106. https://doi.org/10.1063/5.0063534

A strategy is outlined to reduce the number of training points required to model intermolecular potentials using Gaussian processes, without reducing accuracy. An asymptotic function is used at a long range, and the crossover distance between this mo... Read More about Gaussian process models of potential energy surfaces with boundary optimization.

Direct observation of long chain enrichment in flow-induced nuclei from molecular dynamics simulations of bimodal blends (2021)
Journal Article
Anwar, M., & Graham, R. S. (2021). Direct observation of long chain enrichment in flow-induced nuclei from molecular dynamics simulations of bimodal blends. Soft Matter, 2021(10), 2872-2882. https://doi.org/10.1039/d0sm01361g

Modelling of flow-induced nucleation in polymers suggest that long chains are enriched in nuclei, relative to their melt concentration. This enrichment has important consequences for the nucle-ation rate and mechanism, but cannot be directly observed... Read More about Direct observation of long chain enrichment in flow-induced nuclei from molecular dynamics simulations of bimodal blends.

Monte–Carlo simulation of crystallization in single‐chain square‐well homopolymers (2020)
Journal Article
Wicks, T. J., Wattis, J. A. D., & Graham, R. S. (2021). Monte–Carlo simulation of crystallization in single‐chain square‐well homopolymers. Polymer Crystallization, 4(1), Article e10146. https://doi.org/10.1002/pcr2.10146

© 2020 Wiley Periodicals LLC We present Monte–Carlo (MC) simulations of the crystallization transition of single-chain square-well homopolymers, with a continuous description of monomer positions. For long chains with short-ranged interactions this s... Read More about Monte–Carlo simulation of crystallization in single‐chain square‐well homopolymers.

Residual alignment and its effect on weld strength in material-extrusion 3D-printing of polylactic acid (2020)
Journal Article
Costanzo, A., Spotorno, R., Candal, M. V., Fernández, M. M., Müller, A. J., Graham, R. S., …McIlroy, C. (2020). Residual alignment and its effect on weld strength in material-extrusion 3D-printing of polylactic acid. Additive Manufacturing, 36, Article 101415. https://doi.org/10.1016/j.addma.2020.101415

© 2020 Elsevier B.V. Gaining a molecular understanding of material extrusion (MatEx) 3D printing is crucial to predicting and controlling part properties. Here we report the direct observation of distinct birefringence localised to the weld regions b... Read More about Residual alignment and its effect on weld strength in material-extrusion 3D-printing of polylactic acid.

PolySTRAND Model of Flow-Induced Nucleation in Polymers (2020)
Journal Article
Read, D. J., McIlroy, C., Das, C., Harlen, O. G., & Graham, R. S. (2020). PolySTRAND Model of Flow-Induced Nucleation in Polymers. Physical Review Letters, 124(14), https://doi.org/10.1103/physrevlett.124.147802

We develop a thermodynamic continuum-level model, polySTRAND, for flow-induced nucleation in polymers suitable for use in computational process modeling. The model's molecular origins ensure that it accounts properly for flow and nucleation dynamics... Read More about PolySTRAND Model of Flow-Induced Nucleation in Polymers.

Nonlinear shear of entangled polymers from nonequilibrium molecular dynamics (2019)
Journal Article
Anwar, M., & Graham, R. S. (2019). Nonlinear shear of entangled polymers from nonequilibrium molecular dynamics. Journal of Polymer Science Part B: Polymer Physics, 57(24), 1692-1704. https://doi.org/10.1002/polb.24904

This work aims to improve the use of Molecular Dynamics simulations of Kremer-Grest chains to inform future developments of models of entangled polymer dynamics. We perform non-equilibrium molecular dynamics simulations, under shear flow, for well en... Read More about Nonlinear shear of entangled polymers from nonequilibrium molecular dynamics.

Molecular dynamics simulations of crystal nucleation in entangled polymer melts under start-up shear conditions (2019)
Journal Article
Anwar, M., & Graham, R. S. (2019). Molecular dynamics simulations of crystal nucleation in entangled polymer melts under start-up shear conditions. Journal of Rheology, 150(8), https://doi.org/10.1063/1.5082244

Understanding the flow induced crystallisation (FIC) process is necessary due to its technological relevance to polymer processing. Polymer crystallisation controls the morphology of semi-crystalline polymers and hence the properties of the end produ... Read More about Molecular dynamics simulations of crystal nucleation in entangled polymer melts under start-up shear conditions.

Characterising droplet breakup rates of shear-thinning dispersed phase in microreactors (2019)
Journal Article
Wong, V., Loizou, K., Lau, P., Graham, R. S., & Hewkandamby, B. N. (2019). Characterising droplet breakup rates of shear-thinning dispersed phase in microreactors. Chemical Engineering Research and Design, 144, 370-385. https://doi.org/10.1016/j.cherd.2019.02.024

A two-phase flow predictive model with the integration of conservative level-set method (LSM) and Carreau-Yasuda constitutive equation was developed herein. The LSM was chosen as a potential interface capturing scheme for elucidating the interfacial... Read More about Characterising droplet breakup rates of shear-thinning dispersed phase in microreactors.

Understanding flow-induced crystallisation in polymers: a perspective on the role of molecular simulations (2019)
Journal Article
Graham, R. S. (2019). Understanding flow-induced crystallisation in polymers: a perspective on the role of molecular simulations. Journal of Rheology, 63(1), 203-214. https://doi.org/10.1122/1.5056170

Flow induced crystallisation in polymers is an important problem in both fundamental polymer science and industrial polymer processing. The key process of flow-induced nucleation occurs on a very rapid timescale and on a highly localised lengthscale... Read More about Understanding flow-induced crystallisation in polymers: a perspective on the role of molecular simulations.

Active learning in Gaussian process interpolation of potential energy surfaces (2018)
Journal Article
Uteva, E., Graham, R. S., Wilkinson, R. D., & Wheatley, R. J. (2018). Active learning in Gaussian process interpolation of potential energy surfaces. Journal of Chemical Physics, 149(17), 174114. https://doi.org/10.1063/1.5051772

© 2018 Author(s). Three active learning schemes are used to generate training data for Gaussian process interpolation of intermolecular potential energy surfaces. These schemes aim to achieve the lowest predictive error using the fewest points and th... Read More about Active learning in Gaussian process interpolation of potential energy surfaces.

Modelling flow-enhanced crystallisation during fused filament fabrication of semi-crystalline polymer melts (2018)
Journal Article
McIlroy, C., & Graham, R. (2018). Modelling flow-enhanced crystallisation during fused filament fabrication of semi-crystalline polymer melts. Additive Manufacturing, 24, 323-340. https://doi.org/10.1016/j.addma.2018.10.018

Achieving better control in fused filament fabrication (FFF) relies on a molecular understanding of how thermoplastic printing materials behave during the printing process. For semi-crystalline polymers, the ultimate crystal morphology and how it dev... Read More about Modelling flow-enhanced crystallisation during fused filament fabrication of semi-crystalline polymer melts.

Numerical studies of shear-thinning droplet formation in a microfluidic T-junction using two-phase level-set method (2017)
Journal Article
Wong, V. L., Loizou, K., Lau, P., Graham, R. S., & Hewakandamby, B. N. (2017). Numerical studies of shear-thinning droplet formation in a microfluidic T-junction using two-phase level-set method. Chemical Engineering Science, 174, https://doi.org/10.1016/j.ces.2017.08.027

A conservative level-set method (LSM) embedded in a computational fluid dynamics (CFD) simulation provides a useful approach for the studying the physics and underlying mechanism in two-phase flow. Detailed two-dimensional (2D) computational microflu... Read More about Numerical studies of shear-thinning droplet formation in a microfluidic T-junction using two-phase level-set method.

Interpolation of intermolecular potentials using Gaussian processes (2017)
Journal Article
Uteva, E., Graham, R. S., Wilkinson, R. D., & Wheatley, R. J. (2017). Interpolation of intermolecular potentials using Gaussian processes. Journal of Chemical Physics, 147(16), Article 161706. https://doi.org/10.1063/1.4986489

A procedure is proposed to produce intermolecular potential energy surfaces from limited data. The procedure involves generation of geometrical configurations using a Latin hypercube design, with a maximin criterion, based on inverse internuclear dis... Read More about Interpolation of intermolecular potentials using Gaussian processes.

Monte Carlo simulation of single-chain square-well homopolymers (2017)
Journal Article
Wicks, T. J., Wattis, J. A., & Graham, R. (2018). Monte Carlo simulation of single-chain square-well homopolymers. Manuscript submitted for publication

We present Monte Carlo simulations of the crystallisation transition of single-chain square-well homopolymers. We combine parallel tempering with a non-standard choice of tempering levels, a bespoke biasing strategy and a method to map results betwe... Read More about Monte Carlo simulation of single-chain square-well homopolymers.

Surface modification of mild steel using a combination of laser and electrochemical processes (2016)
Journal Article
Speidel, A., Lutey, A. H. A., Mitchell-Smith, J., Rance, G. A., Liverani, E., Ascari, A., …Clare, A. T. (2016). Surface modification of mild steel using a combination of laser and electrochemical processes. Surface and Coatings Technology, 307(A), 849-860. https://doi.org/10.1016/j.surfcoat.2016.09.077

Traditional methods for achieving hierarchical surface structures include highly specified, deterministic approaches to create features to meet design intention. In this study microstructural alteration was undertaken using laser apparatus and second... Read More about Surface modification of mild steel using a combination of laser and electrochemical processes.

Additive manufacture of three dimensional nanocomposite based objects through multiphoton fabrication (2016)
Journal Article
Liu, Y., Hu, Q., Zhang, F., Tuck, C., Irvine, D., Hague, R. J., …Wildman, R. D. (2016). Additive manufacture of three dimensional nanocomposite based objects through multiphoton fabrication. Polymers, 8(9), 1-14. https://doi.org/10.3390/polym8090325

Three dimensional structures prepared from a gold-polymer composite formulation have been fabricated using multiphoton lithography. In this process, gold nanoparticles were simultaneously formed through photoreduction whilst polymerisation of two pos... Read More about Additive manufacture of three dimensional nanocomposite based objects through multiphoton fabrication.

FDCCS16 molecular simulation of the thermophysical properties and phase behaviour of impure CO2 relevant to CCS (2016)
Journal Article
Cresswell, A. J., Wheatley, R. J., Wilkinson, R. D., & Graham, R. S. (in press). FDCCS16 molecular simulation of the thermophysical properties and phase behaviour of impure CO2 relevant to CCS. Faraday Discussions, 192, https://doi.org/10.1039/C6FD00026F

Impurities from the CCS chain can greatly influence the physical properties of CO2. This has important design, safety and cost implications for the compression, transport and storage of CO2. There is an urgent need to understand and predict the prope... Read More about FDCCS16 molecular simulation of the thermophysical properties and phase behaviour of impure CO2 relevant to CCS.