Physical modelling of hydraulic systems results in systems of differential and algebraic equations (DAEs) that are normally stiff. This is because they often include multiple temporal scales and present complex and non-linear behaviour. The simulation of these stiff DAEs in real time demand small time steps, in order to achieve algorithm stability, because explicit fixed step solvers are usuall...

Modified Neglect of Differential Overlap (MNDO) and MNDO/d based semiempirical methods are widely employed to explore structure and thermochemistry of molecular systems. In this work, the AM1/d method has been parametrized for systems containing platinum. The proposed scheme delivers excellent performance for binding energies of Pt complexes with ethylene and large pi conjugated hydrocarbons. T...

Photoswitching of simple photochromic molecules attracts substantial attention because of its possible role in future photon-driven molecular electronics. Here we model the full photoswitching cycle of a minimal photochromic Schiff base-salicylidene methylamine (SMA). We perform semiempirical nonadiabatic on-the-fly photodynamics simulations at the OM2/MRCI level and thoroughly analyze the stru...

The present study analyzed binding of Cu(2+) to tetrapeptides in water solution at several levels of theoretical approximation. The methods used to study the energetic and structural properties of the complexes in question include semiempirical hamiltonians, density functional theory as well as ab initio approaches including electron correlation effects. In order to shed light on the character ...

We study a time-dependent semiempirical method to determine excitation energies, TD-PM3. This semiempirical method allows large molecules to be treated. A Linear-response Chebyshev approach yields the TD-PM3 spectrum very efficiently. Spectra and excitation energies were tested by comparing it with the results obtained using TD-DFT (Time Dependent-Density Functional Theory), using both small an...

We have measured absolute cross sections for ultrafast (femtosecond) single-carbon knockout from polycyclic aromatic hydrocarbon (PAH) cations as functions of He–PAH center-of-mass collision energy in the 10–200 eV range. Classical molecular dynamics (MD) simulations cover this range and extend up to 105 eV. The shapes of the knockout cross sections are well-described by a simple analytical exp...

Three hundred and nine carbon-carbon, carbon-nitrogen, and carbon-oxygen pi-bond lengths in high precision crystal structures of 31 purine and pyrimidine nucleobases were related to the Pauling pi-bond order, its analogues corrected to crystal packing effects, the numbers of non-hydrogen atoms around the bond, and the sum of atomic numbers of the bond atoms. Principal Component Analysis (PCA) a...

We present the results of our recent parametrization of the boron-boron and boron-hydrogen interactions for the self-consistent charge density-functional-based tight-binding (SCC-DFTB) method. To evaluate the performance, we compare SCC-DFTB to full density functional theory (DFT) and wave-function-based semiempirical methods (AM1 and MNDO). Since the advantages of SCC-DFTB emerge especially fo...

Reactions among the monoto polycyclic carbon clusters have been analyzed using semiempirical AM1 and HF/6-31G∗ methods. The C28 (D2) fullerene cage has been considered. Various precursors are chosen with the appropriate carbon belts. It is observed that the reactions between the precursors and the belts are essentially endoergic in nature, whereas the reactions between the stable intermediates ...