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Ab initio simulation applied to the study of materials and nanomaterials has demonstrated its great capacity to obtain and allow us to understand their electronic, structural, dynamic, and other properties. The study of these properties using density functional theory (DFT), with approximations such as LDA or GGA and other functionals, opens up significant possibilities in various fields, including materials science and condensed matter physics. Ab initio simulations are a complementary technique to the experimental study of these properties. The predictive nature of these simulations increases the interest in this type of study, and when combined with experimental studies, they allow for a deeper understanding of the physics and chemistry of materials and nanomaterials under extreme conditions. The objective of this sub-project is to study, using ab initio methods, the electronic, structural, dynamic, and elastic properties of materials and nanomaterials of technological interest, such as ABX4, ABO3, A2X3 compounds and perovskites, under extreme pressure and temperature conditions. All of this is being done in collaboration with the other three experimental projects that are part of this coordinated project. We aim to apply these methods to the study of the aforementioned properties, providing useful information for the synthesis and study of new structural phases that may appear under high pressures, and also obtaining the possible exotic properties that these phases may exhibit. Various methods will be used to search for high-pressure phase candidates in the different compounds, ranging from random search methods to evolutionary methods of a genetic nature and similar approaches. The study of nanocrystals, due to their complexity, will require implementing techniques that allow this type of study to be carried out with a large number of atoms and also to simulate the effect of hydrostatic pressure on the nanostructures. All of this involves developing and verifying the formalism and approaches that allow us to address this type of problem. When the complexity of the system requires it, spin-orbit effects will be taken into account, or DFT+U or hybrid functional methods will be used. Finally, in the optical characterization, in some cases, due to the narrow band gap of some compounds, it will be necessary to go beyond standard DFT theory, using the GW approximation, which will also allow us to study other optical properties of the analyzed systems. We also plan to analyze the charge topology and the chemical aspects of the phase transitions.
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Ab initio simulations applied to the study of materials and nanomaterials have proven their ability to understand the electronic, structural, dynamical properties, etc. The study of these properties using the density functional theory, DFT, with approximations like LDA or GGA, and other functionals, open new possibilities in materials science and condensed matter. Currently, ab initio simulations are a complementary technique for the experimental study of these properties. The predictive nature of these simulations increases the interest of combining the simulations with experimental studies to gain insight in the physics and chemistry of these materials and nanomaterials under extreme conditions. The objective of this project is to study, using ab initio methods, electronic, structural, dynamical and elastic properties of materials and nanomaterials with technological interest, like ABX4, ABO3, A2X3, and perovskites compounds, under extreme conditions of pressure and temperature. All this in collaboration with the other three experimental projects that are part of this coordinated research. We intend to apply these methods to the study of the properties mentioned, providing useful information for the synthesis and the study of new structural phases that can occur under high pressures, obtaining also possible exotic properties that may be present in these phases. In order to look for candidates for high-pressure phases we plan to use different search methods based on different techniques, from random search methods to evolutionary genetic algorithms, and similar methods. The study of nano-crystals due to their complexity will require to implement techniques to perform such studies with a large number of atoms and to include the effect of hydrostatic pressure in nanostructures. We will need to improve the formalism and test different approximations to this problem in order to have an affordable method. In some cases the complexity of the system will require the use of more sophisticated approaches, spin orbit effects, or DFT + U methods, and hybrid functionals. The optical characterization of these materials under extreme conditions, in some cases due to the narrow gap of some compounds, will require to go beyond the standard DFT, we will use the GW approximation and we will also study other optical properties of the systems. We also plan to analyze the charge topology to study chemical aspects of phase transitions.
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