Faculty of Physics University of Warsaw > Events > Seminars > "Nanostructures Theory and Modelling" Seminar

"Nanostructures Theory and Modelling" Seminar

2014/2015 | 2015/2016 | 2016/2017 | 2017/2018 | 2018/2019

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room 1.02, Pasteura 5 at 17:15

dr Marta Galicka (Institute of Physics, Polish Academy of Sciences)

"Rashba splitting of (111) Pb1-xSnxTe Topological Crystalline Insulator Films by bulk Bizmuth doping"

room 1.02, Pasteura 5 at 17:15

mgr Andrzej Skierkowski (IFT UW)

Effects of spin-orbit coupling in 2D systems

Graphene and other 2D atomic systems have emerged recently as promising candidates for charge electronics and for spintronics. Engineering of spintronic devices based on these systems requires quantitative understanding of effects of the spin-orbit coupling in the electronic structure, as well as a possibility to tune spin splitting by external factors, such as decoration of layers with various atoms. I would like to present relativistic ab initio calculations (DFT) of band structure near point K of these crystals, and subsequently a general effective Hamiltonian deduced from the theory of invariants that mimics patterns of DFT.

room 1.02, Pasteura 5 at 17:15

Anita Dudek (FUW)

Dokładność metody Poissona-Boltzmanna w obliczeniach energii swobodnej hydratacji białek

How good are Poisson-Boltzmann calculations for protein hydration free energy?

Białka odgrywają rolę zasadniczo we wszystkich procesach biologicznych. Poznanie struktury i funkcjonowania tych makromolekuł wymaga uwzględniania gęstego środowiska wodnego, w którym się znajdują. Rola efektów hydratacyjnych białek może być analizowana poprzez obliczenia energii swobodnej hydratacji. Zaprezentowane zostaną wyniki precyzyjnych obliczeń energii swobodnej hydratacji białek metodą explicit i implicit solvent. Omówiona zostanie dokładność stosowanej metody PBSA (ang. Poisson-Boltzmann Surface Area) oraz problem doboru optymalnych parametrów: stałej dielektrycznej białka oraz napięcia powierzchniowego.

Proteins play crucial role in virtually all biological processes. Although our attention usually focuses just on the details of protein molecular structures, we shouldn’t forget that they naturally function in a dense aqueous environment. In theoretical approaches, the role of water can be investigated by calculations of hydration free energy. In order to quantify such solvent effects we developed a protocol allowing for precise calculations of protein hydration free energy with explicit and implicit solvent model. The comparison of results with estimates obtained with Poisson-Boltzmann method allows the assessment of accuracy of this most widely used implicit solvent model and shed light on problem with two important parameters: protein dielectric constant and surface tension.

room 1.02, Pasteura 5 at 17:15

dr Magdalena Popielska (IFT UW)

Van der Waals study of hydrogenated and fluorinated graphene layers on Ni(111) substrate

In this lecture, I will present the results of influence of Ni(111) substrate on the hydrogenated and fluorinated graphene layer and will show its impact on energetics, electronic and magnetic properties of such system. For these studies, I employ the density functional theory (DFT) based numerical packages. All of these calculations are done in the framework of the adiabatic-connection fluctuation-dissipation theorem (AC-FDT) in the random phase approximation (RPA), which have been proved to lead to natural inclusion of the nonlocal van der Waals interactions implemented in the VASP package. The comparison between the AC-FDT method and recently published results based on the semi-empirical vdW functionals and force-field corrections, known as a family of DFT-D, will be considered

room 1.02, Pasteura 5 at 17:15

mgr Anna Szumska (Imperial College, London)

Thermoelectric properties of two-dimensional materials based on silicon and germanium

The amount of energy consumed by humans has soared dramatically in the last decades. To meet the demand we cannot only afford any losses but need to develop new clean sources. Nevertheless it appears that only 34% of energy contained in natural resources is used to power actual devices. The rest 66% is simply wasted, mainly as emitted heat. Converting heat into electrical current, which is called thermoelectric effect, is one of the possibilities of reusing thermal radiation. The effect requires specific materials’ properties that are difficult to discern. Previous publications reported that the promising thermoelectric material is Si and Ge and that two-dimensional structure improves thermoelectric efficiency. Thus, we investigated numerically 2-D nanoribbons made of atoms of Si, Ge, and both of them with and without defects implemented. Here, I will present the theoretical approach of thermoelectric effect and the results of transmission calculations.

room 1.02, Pasteura 5 at 17:15

mgr Jaromir Panas (IFT UW)

Study of the Bose-Hubbard type models with Bosonic Dynamical Mean Field Theory

Fast development of techniques and growing number of results of experiments with cold atoms in optical lattices create a growing demand for theoretical description of observed phenomena. The Bose-Hubbard model is well suited for this task. However, solving this model poses a formidable challenge in itself, and some approximation scheme is needed, such as dynamical mean-field theory. In my talk I present basic concepts of this method. I show how it compares to alternative approximation schemes. Finally I present our recent results for the Bose-Hubbard model extended by an infinite-range interaction term.

room 1.02, Pasteura 5 at 17:15

Mikołaj Sadek (IFT UW)

Modeling of boron nitride/graphene heterostructures

room 1.02, Pasteura 5 at 17:15

Shiva Safai (Institute of Physics, Polish Academy of Sciences)

"Quantum Spin Hall Effect in IV-VI Topological Crystalline Insulators"

Topological insulators (TIs) are a new class of quantum matter withinsulating bulks and conducting edge/surface states which are protected bythe time-reversal symmetry. Topological Crystalline insulators (TCIs) havesimilar features like TIs, though crystal symmetries protect these states.It will be shown that thick films of (Pb,Sn)Te and (Pb,Sn)Se, for highenough content of Sn when the band gap is inverted, are TCIs whose helicalDirac-like surface states are protected by mirror symmetries.However, (111)-oriented ultrathin films of such materials exhibit quantumspin Hall phase (or 2D TI), which is due to the intersection of thevalence and conduction bands within particular thicknesses. Suchpredictions will be demonstrated and endorsed by electric band structuresand edge spectral function calculation

room 1.02, Pasteura 5 at 17:15

dr Krzysztof Cendrowski (West Pomeranian University of Technology)

Sandwich-like mesoporous silica for anticancer drug transport - Synthesis, characterizatio, in-vitro and in-vivo study

Carbon and silica nanostructures are often studied due to their physiochemical properties and knowledge on the nanostructures synthesis and functionalization techniques. The following contribution presents in vitro and in vivo studies on the silica nanostructures with potential anticancer application. The core-shell mesoporous silica nanospheres were studied in the in vitro and in vivo, in therms of their biocompatibility and potential anticancer application as a drug carrier. Additional studies on the selected nanostructures stability showed tendency to degrade in the environment imitating conditions in the living organism. Based on the obtained results, assessment of applications’ efficiency of the nanomaterials has been performed.

room 1.02, Pasteura 5 at 17:15

Alexandra Siklitckaia (IFT UW)