Colóquios

PRÓXIMOS COLÓQUIOS

VOLTAMOS EM 2022

COLÓQUIOS ANTERIORES

Palestrante: Prof. Dr. Gustavo M. Dalpian (CCNH/UFABC)
Título: Métodos teórico-computacionais para o design e descoberta de novos materiais
Data: 02/12 às 16h – Formulário para a carta pública de comparecimento
Assistir e Link para participante

Resumo: A área de modelagem computacional de materiais teve grandes avanços nas últimas décadas. O advento da Teoria do Funcional da Densidade fez com que simulações de primeiros princípios se tornassem corriqueiras. O concomitante desenvolvimento de computadores cada vez mais rápidos fez com que a modelagem de um grande número de materiais fosse possível, levando a área para a era do ‘Big Data’. Neste colóquio discutirei os principais avanços da área, e mostrarei alguns exemplos de aplicações, envolvendo simulações em modo ‘high thoughput’ para o entendimento do desdobramento de spin (Rashba) em materiais semicondutores bidimensionais. Também discutirei alguns avanços relacionados a métodos de inteligência artificial (machine learning), focando principalmente na interpretabilidade dos resultados.

Palestrante: Profa. Dra. Mathilde Champeau (CECS/UFABC)
Título: Bioactive-releasing polymers: a supercritical approach for CO2 valorization
Data: 25/11 às 16h – Formulário para a carta de comparecimento
Assistir e Link para participante

Resumo: Mathilde Champeau se formou na França e realizou o seu doutorado entre a França e a Bélgica, focando no uso do CO2 supercrítico para impregnar fármacos em implantes poliméricos. Professora do Centro de Engenharia, Modelagem e Ciências Sociais Aplicadas na UFABC desde 2017, ela coordena o « Laboratório de Tecnologia de CO2 Supercrítico e Materiais Poliméricos » que visa explorar o uso de tecnologia supercrítica para desenvolvimento de polímeros funcionais e valorização do CO2.

Palestrante: Prof. Dr. Caetano Rodrigues Miranda (IF/USP)
Título: Interactive materials design towards a sustainable world
Data: 18/11 às 16h – Carta de comparecimento
Assistir e Link para participante

Resumo: This talk will present recent contributions on computational materials discovery, ranging from carbon neutralization to energy transition [1-2]. Here, we have been inspired by the Sustainable Development Goals (SDGs) by the United Nations and the social role of Physics and Materials Science in developing technologies for a sustainable world. We apply a combination of data analytics and multiscale materials modeling to accelerate the materials discovery process and unveil the molecular mechanisms behind catalytic processes. Here, we focused on a multiscale approach, involving ab initio calculations, molecular dynamics, and machine learning for the development of new technologies on the i) discovery of low- modulus metallic alloys (Ti-Nb-Zr) for biomedical implants, which have also been designed and tested by finite element methods, ii) in the processes for conversion of CO2 and its geochemical capture through mineralization and clays, iii) gas separation, such as membranes, aiming at reducing CO2 emissions and flue gas separation [1-2]. The fluid-material interactive design is also enhanced through perceptual experiences with interactive visualization techniques in virtual reality to design new materials and processes at multiple scales. The newly USP-DIGITAL lab facilities on interactive materials design available at IFUSP for the community will be presented.
Acknowledgments: FAPESP, CNPq, and RCGI.
[1] Miranda et al., JACS 143 4268 (2021)
[2] Miranda et al., The Journal of Physical Chemistry C 124, 26222 (2020)

Palestrante: Prof. Dr. Ricardo Reis (EMA/LNLS)
Título: Understanding Quantum Materials by X-Ray Techniques under extreme conditions
Data: 11/11 às 16h – Carta de comparecimento
Link para Ouvinte: https://youtu.be/-NqsKVUqIZs e Link para participante

Resumo: Many of today’s most exciting and potentially useful materials display states of matter that seem to be explicable only by applying quantum mechanical models. This is perhaps unsurprising as these materials can be host to a complex medley of ingredients that include many-body interactions between spins, electrons and phonons. The ground states frequently exhibit cooperative properties, such as superconductivity, charge or spin-order, Kondo effect, or exotic excitations such as Weyl or Majorana fermions. Besides the fundamental interest in understanding such materials, there is also the prospect of controlling their properties and putting them to use. Therefore, deciphering what causes quantum states of matter to form remains one of the most pressing challenges facing modern physics. In this talk, I will highlight how we can shed light on the building blocks of these materials by a combination of synchrotron techniques (x-ray absorption, diffraction, and scattering) with external pressure (hydrostatic and uniaxial), low temperature and high magnetic field in order to enable a continuous, clean and reversible tuning of quantum correlations. Our aim with is to drive materials through the critical region where the state of matter changes and inherently quantum effects dominate in order to probe the electronic, magnetic and structural properties as a function of lattice contraction. For that I will focus on materials that are on the verge of a phase instability with distinct crystalline structures and with electronic behavior displaying nontrivial topology.

Palestrante: Prof. Dr. Erick Bastos (IQ/USP)
Título: Uma aventura entre Flores, Beterrabas e cores que começou com a UFABC
Data: 04/11 às 16h – Carta de comparecimento
Link: https://youtu.be/S9HaybCpIVc

Resumo: Erick Leite Bastos, Instituto de Química da USP, http://lattes.cnpq.br/1765001992629979
15 anos atrás, eu fui contratado como docente da UFABC e o sonho de transformar moléculas obtidas de plantas em produtos com valor agregado começou. Neste seminário, vou contar a trajetória que nos levou a desenvolver a BeetBlue, um corante pseudo-natural seguro produzido a partir de pigmentos encontrados em flores fluorescentes e na beterraba.

Palestrante: Prof. Dr. Ado Jório (UFMG)
Título: Nano-espectroscopia em materiais bi-dimensionais
Data: 21/10 às 16hCarta de comparecimento
Link: https://youtu.be/YoBbt-vTtDo

Resumo: Neste seminário, o desenvolvimento e aplicacação de um instrumento para nano-espectroscopia óptica serão discutidos. Efeitos de localização espacial em grafeno, mono- e di-calcogenetos de metais de transição serão abordados, com enfoque no campo da twistrônica.

Palestrante: Prof. Dr. Eudes Eterno Fileti ( Unifesp)
Título: Supercapacitores: Maximizando a eficiência no armazenamento de energia eletroquímica
Data: 14/10 às 16hCarta de comparecimento
Link: https://youtu.be/aOUPNNdY1FI

Resumo: Os supercapacitores são certamente uma das classes mais promissoras de dispositivos de armazenamento de energia eletroquímica. Com características entre os capacitares convencionais e as baterias eles têm mostrado enorme potencial tecnológico. Nesse seminário você vai compreender o funcionamento de um supercapacitor e ter noção de como a modelagem computacional tem sido usada para promover a busca constante pela otimização do desempenho destes dispositivos.

Palestrante: Prof. Dr. Alexandre R. Rocha
Título: How Machine can help us learn about water: neural networks applied to liquids
Data: 07/10 às 16hCarta de comparecimento
Link: https://youtu.be/Trz4v5SAAjA

Resumo: Water is, undoubtedly, one of the most important substances known. It is a key resource required for the existence of life as we know. Albeit the liquid is formed by a seemingly simple molecule, the interplay between long and short range interactions at the atomic and molecular level leads to a set of properties that make this liquid so unique. In that sense, accurate microscopic theoretical predictions are hard to come by.
On the one hand, classical force fields used to simulate the dynamics of the liquid, typically require some experimental input. In that sense, they are usually good for computing some physical quantities, while failing in other cases. On the other hand, first principles methods such as density functional theory, are usually limited to small systems and short times scales and good predictive capabilites are hindered by the approximations to the exchange and correlation approximations that are inherent to the method. In this talk I will address some of these issues, and how neural networks fitted on top of accurate density functional calculations can help us understand the properties of bulk water. In particular, I will show how we can obtain force fields that allow us to accurately simulate large systems and long time scales. I will argue that this is extremely important for obtaining good comparison with experimental results.

Palestrante: Prof Dr Alexandre Fontes da Fonseca
Título: Twisting twisted graphene nanoribbons without twisting
Data: 30/09 às 16h – Carta de comparecimento
Link: https://youtu.be/IYpZCQoRVdc

Resumo: The common sense regarding twisting or untwisting a ribbon is that it requires the application of an external rotation to happen. However, at nanoscale, the application of precise  amounts of rotation on a nanoribbon is not a trivial task. Here, the concept of an alternative method to add  twist to or remove twist from a twisted graphene nanoribbon (TGNR) without rotation is presented and computationally demonstrated. The possibility of fine-tuning the amount of twist of a  TGNR is also shown. Besides being capable of precisely determining the  total twist of a TGNR, this concept reveals a twist to writhe transition phenomenon  that is tension-free and does not require controlling either the nanoribbon end-to-end distance or its critical  twist density.

Palestrante: Profa Dra Ana Flávia Nogueira
Título: Metal halide perovskites: a journey through structure, properties and stability
Data: 23/09 às 16h – Carta de comparecimento
Link: www.youtube.com/watch?v=iaUFNG2exGE

Resumo: Metal halide perovskite solar cells have reached the recent efficiency breakthrough of 25.5%. Such fantastic result was only possible due to a precise control and engineering of the morphology, interfaces and the use of multiple cations in perovskite A-site, as Rb, Cs, MA and FA. For tandem perovskite solar cells, a mixture of different anions, as Br and I is also desired to adjust the band gap. Such cocktail of different cations and anions influences the formation of intermediates, phases, favours halide homogenization, etc. In this presentation, we will summarize important results using in situ experiments to probe halide perovskite formation (2D and 3D), stability and composition. We employed time-resolved grazing incidence wide angle x-rayscattering (GIWAXS), small angle x-ray scattering (SAXS) and high-resolution XRD. In situ GIWAXS experiments allowed us to understand the influence of the relative humidity and time to drop the antisolvent during the preparation of perovskite films [1]. It is well known that a 2D layer on the top of a 3D bulk perovskite improves stability and performance. In situ GIWAXS revealed us that during thermal annealing the 2D layer transforms itself into a disorder layer, improving hole transfer and stability [2]. This technique was also employed to identify the first intermediates formed during the degradation of different Cs and Br perovskite compositions under ambient conditions [3]. In situ SAXS is another powerful technique to follow the first stages of the 2D perosvkite’s formation. Our results suggest that the formation of the individual slabs in BA2[FAPbI3]PbI4 is quite fast (within the first 10 s) and, then, these slabs self-assemble into bulk crystallites during the next 40 minutes [4]. [1] R. Szostak, S. Sanchez, P. E. Marchezi, … A. Hagfeldt, A. F. Nogueira, “Revealing the perovskite film formation using the gas quenching method by in situ GIWAXS: morphology, properties and device performance”, Advanced Functional Materials, 31(4) 2007473 (2021) [2] A. Sutanto, R. Szostak, …, A. F. Nogueira, G. Grancini “In Situ Analysis Reveals the Role of 2D Perovskite in Preventing Thermal-Induced Degradation in 2D/3D Perovskite Interfaces”, Nano Letters, 20(5) 3992-3998 (2020) [3] P. E. Marchezi…, M. F. Toney, A. F. Nogueira, “Degradation mechanisms in mixed-cation and mixed-halide CsxFA1-xPb(BryI1-y)3 perovskite films under ambient conditions” J. Mater. Chem. A,9, 9302-9312 (2020) [4] R. F. Moral, L. G. Bonato, J. C. Germino, W. X. Oliveira, R. Kamat, J. Xu, C. Tassone, D. D. Stranks, M. F. Toney, A. F. Nogueira, “Synthesis of Polycrystalline Ruddlesden-Popper Organic Lead Halides and Their Growth Dynamics”, Chemistry of Materials, 31 (22) (2019), 9472-947. Caso você faça parte do programa da pós entre em contato para participar da webconferência.