Assistant Professor of Chemistry
Oakland University, Department of Chemistry
I am an assistant professor at Oakland University. I have joined the Department of Chemistry in the fall of 2011. I came to the USA after receiving my Ph.D. degree in January 2004 and became a member of Professor Piotr Piecuch’s research group at Michigan State University.
Oakland University, Department of Chemistry
Michigan Technological University, Department of Chemistry
Michigan State University, Department of Chemistry
Michigan State University, Department of Chemistry
Ph.D. in Chemistry
University of Silesia, Poland, Department of Theoretical Chemistry, Faculty of Mathematics, Physics and Chemistry
Postgraduate Studies in Software Engineering
Jagiellonian University, Poland
Faculty of Mathematics, Physics and Chemistry
University of Silesia, Poland
I graduated from the University of Silesia in Katowice (Poland), where I was a member of Professor Stanislaw A. Kucharski’s group. In Professor Kucharski’s group I worked on implementing the full inclusion of the triple excitations into the equation of motion coupled cluster method. This was one of the first two implementations of EOMCCSDT ever. I continued to develop coupled cluster methods in Professor Piecuch’s group focusing on new ideas such as the renormalized and open-shell coupled cluster theories and their multi-reference extensions. Using our own computer codes we did applications that range from small systems to large molecules (e.g. systems relevant to metalloenzymes), and we were also able to perform ab initio coupled cluster calculations for nuclei.
In Professor Piecuch’s group, we have developed effcient, fully vectorized computer codes for completely renormalized coupled cluster methods based on the biorthogonal formulation of the method of moments of coupled cluster equations. We have implemented our new codes in the GAMESS software package. This has allowed us to carry out large scale calculations for several important reaction mechanisms and systems consisting transition metal atoms relevant to study of oxygen activation by metalloenzymes. We were also working on an extremely interesting project in collaboration with Dr. David J. Dean and Dr. Thomas Papenbrock from Oak Ridge National Laboratory and Professor Morten Hjorth-Jensen from the University of Oslo in Norway, in which we have applied the standard and renormalized coupled cluster techniques to study ground-and excited-state energies and properties of nuclei.
The main objective of my work at OU is to design and apply quantum-chemical methods that enable precise and effcient determination of potential energy and property surfaces for both existing and hypothetical molecular systems in their ground and excited states. My research combines the development of new ab initio methods and algorithms, as well as the computational exploration of important chemical problems. As I am already a co-author of a popular chemical software package GAMESS, I structure all my computer codes so that they could easily become a part of that software and be distributed freely around the world. Recently, I have added the open-shell extension of the CR-CC(2,3) method into the GAMESS package, which will give us a much wider range of possible applications.
Completely renormalized (CR) coupled-cluster (CC) approaches, such as CR-CCSD(T), in which one corrects the standard CC singles and doubles (CCSD) energy for the effects of triply (T) and other higher-than-doubly excited clusters [K. Kowalski and P. Piecuch, J. Chem. Phys. 113, 18 (2000)], are reformulated in terms of the left eigenstates ⟨Φ∣ℒ⟨Φ∣L of the similarity-transformed Hamiltonian of CC theory. The resulting CR-CCSD(T)ℒCR-CCSD(T)L or CR-CC(2,3) and other CR-CCℒCR-CCL methods are derived from the new biorthogonal form of the method of moments of CC equations (MMCC) in which, in analogy to the original MMCC theory, one focuses on the noniterative corrections to standard CC energies that recover the exact, full configuration-interaction energies. One of the advantages of the biorthogonal MMCC theory, which will be further analyzed and extended to excited states in a separate paper, is a rigorous size extensivity of the basic ground-state CR-CCℒCR-CCL approximations that result from it, which was slightly violated by the original CR-CCSD(T) and CR-CCSD(TQ) approaches. This includes the CR-CCSD(T)ℒCR-CCSD(T)L or CR-CC(2,3) method discussed in this paper, in which one corrects the CCSD energy by the relatively inexpensive noniterative correction due to triples. Test calculations for bond breaking in HF, F2, and H2O indicate that the noniterative CR-CCSD(T)ℒCR-CCSD(T)L or CR-CC(2,3) approximation is very competitive with the standard CCSD(T) theory for nondegenerate closed-shell states, while being practically as accurate as the full CC approach with singles, doubles, and triples in the bond-breaking region. Calculations of the activation enthalpy for the thermal isomerizations of cyclopropane involving the trimethylene biradical as a transition state show that the noniterative CR-CCSD(T)ℒCR-CCSD(T)L approximation is capable of providing activation enthalpies which perfectly agree with experiment.
The equation-of-motion coupled-cluster method with the full inclusion of the single, double, and triple excitations (EOM-CCSDT) has been formulated and implemented. The proper factorization procedure ensures that the method scales as n8,n8, i.e., in the same manner as the standard CCSDT method for ground states. The method has been tested on the vertical excitation energies of the N2N2 and C0 molecules for several basis sets up to 92 basis functions. The full inclusion of the triple excitations improves the EOM-CCSD results by up to 0.2 eV for considered systems.
We propose the non-iterative, completely renormalized (CR) coupled-cluster (CC) approaches, including the CR-CC(2, 3) method which offers considerable improvements over the CCSD(T) approach without a significant increase in the computer effort. The CR-CC(2, 3) method, in which the CCSD (CC singles and doubles) energy is corrected for the effect of triples, is size extensive, competitive with CCSD(T) in calculations for non-degenerate states, and as accurate as the expensive CC approach with singles, doubles, and triples in the bond-breaking region. Calculations of the activation enthalpy for the thermal isomerizations of cyclopropane involving trimethylene suggest that CR-CC(2, 3) may be applicable to biradicals..
The recently formulated completely renormalized coupled-cluster method with singles, doubles, and noniterative triples, exploiting the biorthogonal form of the method of moments of coupled-cluster equations (Piecuch, P.; Włoch, M. J. Chem. Phys. 2005, 123, 224105; Piecuch, P.; Włoch, M.; Gour, J. R.; Kinal, A. Chem. Phys. Lett. 2006, 418, 467), termed CR-CC(2,3), is extended to open-shell systems. Test calculations for bond breaking in the OH radical and the ion and singlet−triplet gaps in the CH2, HHeH, and (HFH)- biradical systems indicate that the CR-CC(2,3) approach employing the restricted open-shell Hartree−Fock (ROHF) reference is significantly more accurate than the widely used CCSD(T) method and other noniterative triples coupled-cluster approximations without making the calculations substantially more expensive. A few molecular examples, including the activation energies of the C2H4 + H → C2H5 forward and reverse reactions and the triplet states of the CH2 and H2Si2O2 biradicals, are used to show that the dependence of the ROHF-based CR-CC(2,3) energies on the method of canonicalization of the ROHF orbitals is, for all practical purposes, negligible.
Accurately describing the relative energetics of alternative bis(μ-oxo) and μ-η2:η2 peroxo isomers of Cu2O2 cores supported by 0, 2, 4, and 6 ammonia ligands is remarkably challenging for a wide variety of theoretical models, primarily owing to the difficulty of maintaining a balanced description of rapidly changing dynamical and nondynamical electron correlation effects and a varying degree of biradical character along the isomerization coordinate. The completely renormalized coupled-cluster level of theory including triple excitations and extremely efficient pure density functional levels of theory quantitatively agree with one another and also agree qualitatively with experimental results for Cu2O2 cores supported by analogous but larger ligands. Standard coupled-cluster methods, such as CCSD(T), are in most cases considerably less accurate and exhibit poor convergence in predicted relative energies. Hybrid density functionals significantly underestimate the stability of the bis(μ-oxo) form, with the magnitude of the error being directly proportional to the percentage Hartree−Fock exchange in the functional. Single-root CASPT2 multireference second-order perturbation theory, by contrast, significantly overestimates the stability of bis(μ-oxo) isomers. Implications of these results for modeling the mechanism of C−H bond activation by supported Cu2O2 cores, like that found in the active site of oxytyrosinase, are discussed.
I would be happy to talk to you if you need my assistance.
You can find me at my office located in 269 Mathematics and Science Center (MSC) at Oakland University
I am at my office every day from 9:00 A.M. until 4:00 P.M., but you may also consider a call or email me to schedule an appointment.