Leandro Liborio

Leandro Liborio

Computational Scientist at STFC

Posts by Collection

publications

Stability of Sr Adatom Model Structures for SrTiO3(001) Surface Reconstructions

Published in Journal of Physics: Condensed Matter, 2005

In this work we studied the atomic scale structure of the (001) surface of Strontium Titanate. We proposed a model to explain a set of experimentally observed reconstructions of the (001) surface of strontium titanate (Kubo and Nozoye 2003 Surf. Sci. 542 177).

Recommended citation: L. Liborio, C. Sanchez, A. Paxton and M. Finnis. J. Phys.: Condensed Matter. 17, L223- L230, (2005). http://iopscience.iop.org/article/10.1088/0953-8984/17/23/L01/pdf

Ab initio Atomistic Thermodynamics of the (001) surface of Strontium Titanate

Published in Queen's University Belfast, 2006

In this thesis I studied the atomic scale models that were proposed to understand the surface reconstructions observed on SrTiO3 (001). I investigated these atomic scale models using first principles calculations. Two newly proposed models for SrTiO3(001) were studied: the so called Sr adatom model and the double layer model. In particular, I have focused on the models proposed to explain the (2×1) and c(4×2) reconstructions on SrTiO3(001), and on the set of surface phase transitions observed by Kubo and Nozoye on SrTiO3(001).

Recommended citation: L. Liborio, PhD Thesis, Queen's University Belfast, 2006

Calculating Charged Defects using CRYSTAL

Published in Journal of Physics: Conference Series, 2010

In this work we presented and discussed a methodology for the calculation of charged defects using the CRYSTAL program. Two example calculations are used to illustrate the methodology: He+ ions in a vacuum and two intrinsic charged defects, Cu vacancies and Ga substitution for Cu, in the chalcopyrite CuGaS2.

Recommended citation: C. Bailey, L. Liborio, G. Mallia, S. Tomic and N. Harrison. Journal of Physics: Conference Series, 242, 012004, 2010. http://iopscience.iop.org/article/10.1088/1742-6596/242/1/012004/pdf

A hybrid density functional study of structural, bonding, and electronic properties of the manganite series: La1−xCaxMnO3 (at x=0, 1/4 and 1)

Published in Physical Review B, 2014

In this work we doped a Manganate with extrinsic defects and analyzed the effects of the doping on the magnetic and electronic properties of the Manganate.

Recommended citation: Korotana, Romi, Mallia, Giuseppe, Gercsi, Zsolt, Liborio, Leandro, Harrison, Nicholas, Physical Review B, 89, 205110, 2014 https://journals.aps.org/prb/abstract/10.1103/PhysRevB.89.205110

Exploring the Temperature Dependent Solid-State ALC Spectrum of the C6H6Mu• Radical with Ab-Initio Simulation Techniques

Published in Japanese Journal of Physics: Conference Series, 2017

In this work, we used a number of different computational techniques to study the temperature dependence of the Avoided Level Crossing spectrum of crystalline benzene.

Recommended citation: Sturniolo S, Liborio L, Pratt F L, Cottrell S P, Jochym D B, Montanari B, Proceedings of the 14th International Conference on Muon Spin Rotation, Relaxation and Resonance (μSR2017). http://journals.jps.jp/doi/10.7566/JPSCP.21.011036

Computational Prediction of Muon Stopping Sites

Published in The Journal of Chemical Physics, 2018

The stopping site of the muon in a muon-spin relaxation experiment (mu+SR) is generally unknown and there few techniques that can be used to determine the muon stopping site. In this work, we propose a purely theoretical method that can be used to predict muon stopping sites in crystalline materials using only computer simulations.

Recommended citation: Computational Prediction of Muon Stopping Sites, L. Liborio, S. Sturniolo and D. Jochym, The Journal of Chemical Physics, 148, 134114 (2018) https://aip.scitation.org/doi/full/10.1063/1.5024450

Comparison between Density Functional Theory and Density Functional Tight Binding approaches for finding the muon stopping site in organic molecular crystals

Published in The Journal of Chemical Physics, 2019

The stopping site of the muon in a muon-spin relaxation experiment (mu+SR) is generally unknown and there few techniques that can be used to determine the muon stopping site. In this work, we compare the accuracy and computational costs of two purely theoretical methods that can be used to predict muon stopping sites in organic crystalline materials using only computer simulations.

Recommended citation: Comparison between Density Functional Theory and Density Functional Tight Binding approaches for finding the muon stopping site in organic molecular crystals, arXiv:1812.02999 [physics.comp-ph] https://aip.scitation.org/doi/10.1063/1.5085197

talks

The Electronic Structure of the Ti4O7 Magneli Phase

Published:

In this work we used DFT to study the electronic structure of the Ti4O7 Magneli phase. We proposed a model to explain the unusual behaviour of the electronic structure of this this phase as a function of temperature

Combining MuSR and DFT

Published:

This talk describes how DFT calculations have been used to understand results from muon experiments. The talk describes the status of computer simulations applied to MuSR experiments and which are the main problems and challenges that need to be addressed. Essentially, I presented a summary of the main ideas behind DFT and how this technique has been used in combination with muon experiments.

Computational Prediction of Muon Stopping Sites in Silicon

Published:

In this work, I focused on the paramagnetic states formed by muons in semiconductors. In particular, I revisited the case of muons in pure Si, and use a combination of computational methods to estimate the muon stopping site and the temperature dependance of the muon’s hyperfine parameters.

Computer Simulations for Interpreting μSR Experiments

Published:

In this work, I presented the key concepts and the main approximations used in our computer models, and also discussed why some of these approximations are relevant to muon experiments. In particular, I talked about DFT and how it can be used to study muonated molecular and crystalline systems. In particular, I presented a method that we are developing to predict the muon stopping sites in crystalline materials.

Simulaciones Computacionales en la Interpretación de Experimentos a Gran Escala: el Caso de los Muones

Published:

En esta charla presenté muy brevemente al Laboratorio Rutherford Appleton y a describí como se generan y se usan las partículas subatómicas denominadas muones. Los experimentos con muones se utilizan en áreas muy variadas, que van desde química orgánica hasta física de semiconductores. El foco de esta charla fue la presentación de una serie de métodos computacionales que hemos desarrollado para ayudar en la interpretación de los diferentes tipos de experimentos con muones. Estos métodos combinan cálculos de primeros principios con técnicas de aprendizaje automatizado (machine learning), y nos han permitido identificar parámetros que son cruciales para los experimentos con muones, tales como el sitio de implante del muon en estos experimentos.

Computer Simulations for Interpreting µSR Experiments: Beyond DFT

Published:

In this work, I discussed the computational methods that we had developed so far to estimate the muon stopping site in crystalline materials. The key new concept is the development of methods based on calculations other than ab-initio calculations. The idea is that the new calculations are computationally faster than the purely ab initio ones. One of the methods that I have tested is the DFT-based Tight-Binding.

NOMAD Summer

Published:

In this poster, I presented a summary of the computational methods that we had developed so far to estimate the muon stopping sites in crystalline materials. The poster presented the Unperturbed Electrostatic Potential method, our ab initio-based method and also the new methods based on Tight-Binding calculations.

2019 Fall Meeting EMRS

Published:

In this poster, I presented the computational modelling work that I had been doing on the lithium amide-imide solid solution. The work focused on understanding the structure of this solid solution and on how modelling could help interpret experimental results.

Computer Simulations for Interpreting μSR Experiments

Published:

This was a seminar that I gave during my visit to the Paul Scherrer Institute (PSI), which hosts one of the two muon sources in Europe. The visit was part of my Software Sustainability Institute fellowship. In the seminar, I presented the computational models and associated tools that are being developed at the Rutherford Appleton Laboratory (RAL), and discussed some potential avenues for collaborative work- centred on muon software development- between PSI and RAL.

teaching