Research & Projects

We offer new positions for both graduate and undergraduate students to participate at a Junior Star research project, doing computational/theoretical work in our lab at UCT Prague. We also collaborate with leading pharmaceutical companies located in Czechia. Please, contact Dr. Červinka for additional details.

Open positions related to this project:

• Post-doctoral fellow working on incorporation of fragment-based ab initio calculations of cohesive energies of amorphous solids into a Monte Carlo sampling protocol

• PhD student working on benchmarking classical and quantum simulation tools for predictions of polymorphism and melting of molecular crystals

• PhD student working on a machine learning protocol for modeling non-covalent interactions from first principles

• Undergraduate students with motivation to learn how to run complex ab initio simulations of structural, thermodynamic and electronic properties of condensed materials

Past research projects

Ionic liquids (ILs) possess a vast potential for numerous technologies (gas capture, smart electrolytes, nanoparticles exfoliation media, etc.), as ILs possess unique properties such as low volatility, large electrochemical window or a boundless structural variability. Broader exploitation of their beneficial characteristics is impeded by their cost, limited availability of the physico-chemical data or an insufficient understanding of ILs-related phenomena. Known for a century and considered nonvolatile for decades, ILs were proved to possess a non-zero saturated vapor pressure only a decade ago. Still, volatility of ILs is lower by orders of magnitude when compared to common molecular solvents. Such an extremely low volatility is a principal obstacle impeding reliable and reproducible measurements of their vaporization data. Significance of these properties for extremely low-volatile chemical species can be illustrated by the environmental distribution of highly persistent compounds, considered almost non-volatile. These, however, spread via the atmosphere even to the polar regions, where they concentrate in plants, animal or human tissues, acting as mutagens subsequently. Data on volatility of chemical speciesare the key inputs for modelling the environmental distribution of pollutants. A rigorous methodology, capable of accurate determinations of the volatility of ILs, which would be based on more reliable approaches (combining experiments and first-principles calculations) than the direct measurements of vapor pressures of ILs would certainly find use in the future process design and selection of suitable ILs. Especially if there are millions of relevant ILs systems, while the thermodynamic data exist for hundreds of ILs.

The term cohesive properties unites the cohesive/lattice energy of a crystal and its sublimation or vaporization enthalpy. Knowledge of the sublimation enthalpy at the temperature of the triple point and the enthalpy of fusion enables to obtain the vaporization enthalpy. Enthalpy of fusion for ILs is measurable with a reasonable experimental uncertainty, whereas the sublimation enthalpy of a molecular crystal (solid IL) can be calculated with a fair accuracy from first principles from the cohesive energy and phonon-based properties. High level ab initio fragment-based techniques, periodic quantum-chemical calculations, or their combinations along with the quasi-harmonic approximation capture these properties satisfactorily for molecular crystals. First-principles calculations and molecular dynamics (classical or ab initio) are available for calculations of the thermodynamic properties of the ideal-gas phase of ILs. The given combination of theoretical approaches is unique and as such, it aims at development of a novel promising scheme capable of generating reliable and accurate temperature-dependent data on phase equilibria of ILs.

Development of new medicaments always includes a costly and time-consuming stage of polymorph screening for proposed active pharmaceutical ingredients (API). Physico-chemical properties and stability of all relevant polymorphs need to be determined experimentally under a broad range of conditions to guarantee the safety and efficiency of the drug use. Existence of a general, high-performance and reliable computational methodology, capable of ab initio investigations and predictions of polymorphism, would largely facilitate the pharmaceutical development in the future. Such predictive computations would narrow the scope to be verified experimentally, appreciably saving the amount of the experimental effort in the development of new API. Presented project follows up the latest advance in the field of first-principles predictions of phase behavior for molecular crystals and aims at extending its applicability for systems that remain challenging to treat accurately with the currently available computational methodologies, such as molecular crystals of highly flexible molecules, crystals exhibiting static or dynamic disorder, or highly anisotropic molecular crystals. Both fragment-based and periodic ab initio calculations along with the quasi-harmonic approximations are developed and used to calculate the properties of crystalline API such as the cohesive energy, phonons, Gibbs energies at finite temperatures and pressures, and nuclear magnetic resonance (NMR) spectra, enabling to rank and predict the polymorph stability, as well as to track the subtle relationship of the crystal packing motives to the polymorph properties. As the polymorphs of molecular crystals usually lie very close in terms of their energy, a sub-kJ/mol accuracy needs to be targeted for all involved quantum-chemical and statistical-thermodynamic levels of theory, motivating for their further development within the project. Combining the given computational approaches and the collaboration with leading Czech experimentalists in the filed of calorimetry and vapor pressuess (prof. Růžička at UCT Prague) and NMR crystallography (dr. Brus at IMC Prague) and our American partner (UCR) results in a very deep insight on the addressed phenomena. This project thus benefits from a strong synergy between theory and experiment, extending the limits and possibilities of current computational chemistry in the field of molecular crystals and greatly contributing to the understanding of polymorphism of molecular crystals at the molecular level.