The CCSD(T) method is often called the "gold standard" of computational chemistry, because it is one of the most accurate methods applicable to reasonably large molecules. It is particularly useful for the description of noncovalent interactions where the inclusion of triple excitations is necessary for achieving a satisfactory accuracy. While it is widely used as a benchmark, the accuracy of CCSD(T) interaction energies has not been reliably quantified yet against more accurate calculations. In this work, we compare the CCSD[T], CCSD(T), and CCSD(TQ) noniterative methods with full CCSDTQ and CCSDT(Q) calculations. We investigate various types of noncovalent complexes [hydrogen-bonded (water dimer, ammonia dimer, water ··· ammonia), dispersion-bound (methane dimer, methane ··· ammonia), and π-π stacked (ethene dimer)] using various coupled-clusters schemes up to CCSDTQ in 6-31G*(0.25), 6-31G**(0.25, 0.15), and aug-cc-pVDZ basis sets. We show that CCSDT(Q) reproduces the CCSDTQ results almost exactly and can thus serve as a benchmark in the cases where CCSDTQ calculations are not feasible. Surprisingly, the CCSD[T] method provides better agreement with the benchmark values than the other noniterative analogs, CCSD(T) and CCSD(TQ), and even than the much more expensive iterative CCSDT scheme. The CCSD[T] interaction energies differ from the benchmark data by less than 5 cal/mol on average (for all complexes and all basis sets), whereas the error of CCSD(T) is 9 cal/mol. In larger systems, the difference between these two methods can grow by as much as 0.15 kcal/mol. While this effect can be explained only as an error compensation, the CCSD[T] method certainly deserves more attention in accurate calculations of noncovalent interactions.

The CCSD(T) method stands out among various coupled-cluster (CC) approximations as the "golden standard" in computational chemistry and is widely and successfully used in the realm of covalent and noncovalent interactions. The CCSD(T) method provides reliable interaction energies, but their surprising accuracy is believed to arise partially from an error compensation. The convergence of the CC expansion has been investigated up to fully iterative pentuple excitations (CCSDTQP); for the smallest eight electron complexes, the full CI calculations have also been performed. We conclude that the convergence of interaction energy at noncovalent accuracy (0.01 kcal/mol) for the complexes studied is reached already at CCSDTQ or CCSDT(Q) levels. When even higher accuracy (spectroscopic accuracy of 1 cm(-1), or 3 cal/mol) is required, then the noniterative CCSDTQ(P) method could be used.

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Cieľom príspevku je priblížiť problematiku zodpovednosti zamestnávateľa za pracovné úrazy a choroby z povolania, vymedziť pojmy a bližšie ich špecifikovať. Práca primárne obsahuje značnú časť informácií z právneho predpisu č. 311/2001 Z.z Zákonník práce v znení neskorších predpisov, týkajúcich sa zodpovednosti zamestnávateľa za pracovný úraz a chorobu z povolania, z pohľadu právneho poriadku platného na území Slovenskej republiky. Kľúčové slováZodpovednosť za škodu. Pracovný úraz. Choroba zpovolania. Zamestnávateľ. Zamestnanec. Zákonník práce.