Orbital-based methods for electronic-structure calculations are limited to atoms or molecules with up to about 50 electrons. This limitation comes from the requirement of a long expansion in basis functions to approximate correctly the wave function. Replacing the Coulomb interaction with a smooth model potential has two main consequences: first, the wave function becomes cuspless and the expansion in basis functions converges more rapidly, and second, the smooth potential describes a weaker interaction at the electronic coalescence point, which leads to the loss of accuracy. This work explores whether one can construct models with smooth, non-singular, potentials, but without compromising accuracy. The key idea is to use extrapolation procedures to predict the energy for the Coulomb interaction from a sequence of (cheaper) calculations for smooth potentials. By replacing the Coulomb electron-electron interaction with a smooth potential, using the semi-stochastic heat-bath configuration interaction method (SHCI) to select key configurations, and extrapolating to the limiting (non-smoothed) Coulomb potential, we were able to retain the accuracy of full configuration interaction (FCI) calculations, at reduced computational cost. / Thesis / Doctor of Philosophy (PhD)

By monetary policy decisions, central banks use output gap to keep macroeconomic variables at their natural levels. A substantial disadvantage of this variable is the fact that it is an unobservable variable which is very problematic to measure, although it is possible to estimate it with various methods of estimation. This thesis aims to find the most suitable method of estimation for Czech economy. Thirteen methods have been chosen for this aim: linear trend, quadratic trend, HP filter, band-pass filters, robust trend, univariate unobserved component model, two types of production function, two SVAR models, multivariate HP filter and multivariate unobserved component model. Own estimations have shown that estimated trajectories of unobservable states were not identical. For own selection of the most suitable method of estimation, quantitative (ability to forecast inflation ,a growth of product and data revisions by selected national and international organisations) and qualitative criterions (qualities of methods of estimation, transparency and easy application) have been selected, where emphasis was put on quantitative criterions. Results of this thesis will show that the most suitable method of estimation output gap for Czech economy is multivariate unobserved component model.

Data on elastic scattering of 96 MeV neutrons from 56Fe, 89Y and 208Pb in the angular interval 10-70° are presented. The previously published data on 208Pb have been extended, as a new method has been developed to obtain additional information at the most forward angles. The results are compared with phenomenological and microscopic optical potentials. The theory predictions are in general in good agreement with the experimental data. A study of the deviation of the zero-degree cross section from Wick's limit has been performed. The data on 208Pb are in agreement with Wick's limit, while those on lighter nuclei overshoot the limit significantly. A novel analysis method has been developed to obtain the inelastic neutron emission cross sections from the existing 56Fe data. The method is based on folding a trial spectrum with the response of the detector setup. The data cover the angular interval 26-65° and an excitation energy range of 0-45 MeV, ranges hitherto not studied. The results are compared with nuclear model predictions and found to be in good agreement with the experimental data.

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This study seeks to analyse and quantify cross-border effects of discretionary fiscal policies from two major points of view. The aggregate approach rests on the use of the structural vector autoregression model (SVAR) and its extension, the global vector autoregression model (GVAR). The discretionary fiscal impulse itself is then defined as a change in cyclically adjusted balance of the government sector, calculated at quarterly frequencies. This section is then complemented by a case study of a single measure: the German car scrapping scheme during 2009 and its effects on the Czech economy. It was found that cross-border effects of discretionary fiscal policies may be indeed present, in case certain conditions are met. Importantly, a fiscal impulse has to originate from a sufficiently large economy and there needs to be a tight trade linkage between examined countries. In most cases, cross-border effects have also been found of lesser magnitude than direct impacts of fiscal policies on the domestic country. Finally, as demonstrated on the German-Czech case, even a single fiscal measure can trigger substantial cross-border spillovers. It was estimated that this measure positively contributed to real GDP growth in 2009 in the Czech Republic by 0.44 pp.