J.C.A. Prentice

Room 544
Mott Building
Cavendish Laboratory
J J Thomson Avenue
Cambridge
Cambs
CB3 0HE

Email: jcap3@cam.ac.uk, joseph.prentice@seh.ox.ac.uk

About Me

I completed my PhD in 2018 in the TCM group at the Cavendish Laboratory of the University of Cambridge, supervised by Prof. Richard Needs. I have since moved on, first to work on the linear scaling DFT code ONETEP with Dr. Arash Mostofi and Prof. Peter Haynes at Imperial College London, and more recently to St. Edmund Hall and the Department of Materials at the University of Oxford, as the Cooksey Early Career Teaching and Research fellow. However, I am still a semi-regular visitor to the TCM group in Cambridge.

During my PhD, I worked on investigating anharmonic effects on structure in periodic solids, and how to improve the methods used to calculate these effects. My PhD was funded by the EPSRC, and I was also a member of St. Edmund's College.

My CV can be found here.

PhD Research

My PhD work utilises the method introduced by Bartomeu Monserrat, with Richard Needs and Neil Drummond, to calculate the anharmonic vibrational wavefunctions and energy of various materials, in order to provide an accurate theoretical understanding of their vibrational behaviour. My work focuses on dynamic Jahn-Teller systems and the calculation of their anharmonic properties, such as vacancy defects in diamond and perovskite materials. I also did work on improving this method, by using calculated data that was previously discarded to reduce the computational cost, and also by including coupling between phonons in order to improve accuracy.

More specifically, I applied this method to the neutral vacancy in diamond. The neutral vacancy in silicon is a static Jahn-Teller system, but it is known experimentally that the same defect in diamond is not. It retains the tetrahedral symmetry of the lattice, whilst in silicon a static tetragonal distortion occurs. My work has focused on obtaining an accurate description of this fundamentally anharmonic effect from first principles.

The picture shows a tetragonal distortion around a neutral vacancy in silicon, where the 4 atoms around the vacancy have formed two pairs to lower their energy.

Pre-PhD Work

Before coming to Cambridge, I did a MPhys degree at the University of Oxford, as a member of University College. My MPhys project in my final year was supervised by Dr. Amalia Coldea in the Quantum Materials group, and was on the subject of mapping Fermi surfaces of layered hexagonal materials, particularly PdCoO₂, through modelling angular magnetoresistance oscillations (AMRO). In the course of this work I wrote an AMRO simulation program, AMROSim2D, in MATLAB. I also extended parts of the project over the summer of 2014. The picture shows AMRO calculated by AMROSim2D for the strongly warped Fermi surface inset in the graph, for a variety of magnetic field strengths.

I have also worked at the Rudolf Peierls Centre for Theoretical Physics at Oxford on two occasions. In the summer of 2012 I worked in a administrative capacity, finding and contacting many alumni who had lost touch with the department. In the summer of 2013, I worked with Prof. Fabian Essler and his group, particularly Dr. Maurizio Fagotti and Dr. Imke Schneider, on simulating the out-of-equilibrium dynamics of 1-D spin chains due to quantum quenches. This was done using the time-evolving block decimation (TEBD) method, as implemented by the ALPS project.

Publications

Using forces to accelerate first-principles anharmonic vibrational calculations [arXiv]
J.C.A. Prentice and R.J. Needs
Physical Review Materials 1, 023801 (2017).

First-principles study of the dynamic Jahn-Teller distortion of the neutral vacancy in diamond [arXiv]
J.C.A. Prentice, B. Monserrat and R.J. Needs
Physical Review B 95, 014108 (2017).

Modeling the angle-dependent magnetoresistance oscillations of Fermi surfaces with hexagonal symmetry [arXiv]
J.C.A. Prentice and A.I. Coldea
Physical Review B 93, 245105 (2016).

Presentations

First-principles anharmonic calculations and the dynamic Jahn-Teller effect, CCP9 Young Researchers Event, University of Cambridge, 10 March 2017.

First-principles anharmonic calculations and the dynamic Jahn-Teller effect, American Physical Society March Meeting, New Orleans, 13-17 March 2017.

First-principles anharmonic calculations and the dynamic Jahn-Teller effect, Electronic Structure Discussion Group, TCM, University of Cambridge, 7 December 2016.

Improving anharmonic vibrational calculations from first principles, Electronic Structure Discussion Group, TCM, University of Cambridge, 27 January 2016.

Anharmonic vibrations around the neutral vacancy in diamond and silicon, CCP9 Young Researchers Event, University of York, 25-26 March 2015.

Anharmonic vibrations and the neutral vacancy in diamond and silicon, Electronic Structure Discussion Group, TCM, University of Cambridge, 25 February 2015.

Posters

First-principles anharmonic calculations and the dynamic Jahn-Teller effect, Institute of Physics Theory of Condensed Matter Group Meeting, University of Warwick, 6 June 2017.

First-principles anharmonic calculations and the dynamic Jahn-Teller effect, CCP9 Young Researchers Event, University of Cambridge, 10 March 2017.

First-principles anharmonic calculations and the dynamic Jahn-Teller effect, 18th International Workshop on Computational Physics and Materials Science: Total Energy and Force Methods, ICTP, Trieste, 12-14 January 2017.

Improving anharmonic vibrational calculations from first principles, Deutsche Physikalische Gesellschaft Frühjahrstagung (German Physical Society Spring Meeting), Universität Regensburg, 6-11 March 2016.

Improving anharmonic vibrational calculations from first principles, Total Energy and Force Methods Workshop, Université du Luxembourg, 11-13 January 2016.

Anharmonic vibrations around the neutral vacancy in diamond and silicon, CCP9 Young Researchers Event, University of York, 25-26 March 2015.

Other

Mapping Fermi surfaces of layered hexagonal materials, MPhys project, July 2014. Supervisor: Dr Amalia Coldea.

Teaching

During my time at Cambridge, I supervised Part IB (2nd year) Natural Sciences students at Robinson College in the courses for the Physics A option - Experimental Methods, Oscillations, Waves and Optics, Quantum Physics and Condensed Matter Physics. I am also an Associate Fellow of the Higher Education Academy through being a graduate of the Teaching Associate Programme (TAP), run by the Personal and Professional Development section of the university.

Other Activities

I enjoy acting in student productions, and have appeared in The Play's The Thing (Mansky), A Midsummer Night's Dream (Bottom), The Crucible (Danforth), The Importance of Being Earnest (Lane), The Man of Mode (Old Bellair), She Stoops To Conquer (Diggory), Titus Andronicus (Titus), The Country Wife (Pinchwife) and The Government Inspector (Osip), in reverse chronological order. I occasionally play football (poorly) at college level. The most recent (in)glorious exploits of my old team can be found here.