Výpočetní metody založené na tenzorových sítích pro silně korelované systémy v kvantové chemii

Brandejs, Jan

Despite an immense progress in recent decades, a precise treatment of strongly corre- lated molecular systems still remains a challenge as of today. To help solve this problem, we have developed a massively parallel implementation of DMRG, called MOLMPS. For nonrelativistic systems requiring accurate treatment of both static and dynamical corre- lation, we have extended MOLMPS by the means of the almost linear scaling DLPNO- TCCSD method. In relativistic domain, we are the first who employed the 4c-CCSD to add dynamical correlation on top of DMRG, yielding the 4c-TCCSD method. When tested on benchmarks like the π-conjugated anthracene tetramer with CAS(63,63) and the FeMoco cofactor with CAS(113,76). We showed a good parallel performance on up to about 2000 CPUs. On the example of Iron(II)-Porphyrin model, we showed that the DLPNO-TCCSD captures 99.9% of TCCSD correlation energy. Our spectroscopic study on heavy diatomics showed that the 4c-TCCSD approach increases the precision of underlying CCSD to the order of CCSD(T) and that it is a promising approach. The thesis discusses three different implementations of quantum chemical methods based on QC-DMRG. 1

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