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81.
Jan E. Grabowski 《Journal of Algebraic Combinatorics》2015,42(4):1111-1134
82.
Łukasz Grabowski 《Mathematische Annalen》2015,363(1-2):637-656
83.
From coupled-cluster theory and many-body perturbation theory we derive the local exchange-correlation potential of density functional theory in an orbital dependent form. We show the relationship between the coupled-cluster approach and density functional theory, and connections and comparisons with our previous second-order correlation potential [OEP-MBPT(2) (OEP-optimized effective potential)] [I. Grabowski, S. Hirata, S. Ivanov, and R. J. Bartlett, J. Chem. Phys. 116, 4415 (2002)]. Starting from a general theoretical framework based on the density condition in Kohn-Sham theory, we define a rigorous exchange-correlation functional, potential and orbitals. Specifying initially to second-order terms, we show that our ab initio correlation potential provides the correct shape compared to those from reference quantum Monte Carlo calculations, and we demonstrate the superiority of using Fock matrix elements or more general infinite-order semicanonical transformations. This enables us to introduce a method that is guaranteed to converge to the right answer in the correlation and basis set limit, just as does ab initio wave function theory. We also demonstrate that the energies obtained from this generalized second-order method [OEP-MBPT2-f] and [OEP-MBPT2-sc] are often of coupled-cluster accuracy and substantially better than ordinary Hartree-Fock based second-order MBPT=MP2. 相似文献
84.
Ma?gorzata?Domaga?aEmail author Magdalena?Ma?ecka Katarzyna?Urbaniak Grzegorz?Mlostoń S?awomir?J.?Grabowski 《Structural chemistry》2005,16(1):55-59
The crystal structures of dimethyl 2,2,4,4-tetramethyl-3-oxocyclobutane-1-spiro-5-3,4-diphenyl-(1,3)-thiazolidine-2,2-dicarboxylate, C26H29NO5S for V, and dimethyl 3,4-diphenyl-5-isopropylidene-(1,3)-thiazolidine-2,2-dicarboxylate, C22H23NO4S for VI, have been solved. The 1,3-thiazolidine ring of compound V has got twisted conformation, while in compound VI this ring adopts envelope. In both structures short inter- and intramolecular contacts were found, which can be recognized as hydrogen bonds. 相似文献
85.
An efficient, stereospecific synthesis of the alkaloids senepodine G (2) and cermizine C (1) has been completed using the BF3.Et2O-promoted stereospecific addition of Me2CuLi to alpha,beta-unsaturated lactam 6 to provide lactam 3, the addition of MeMgBr followed by HCl to convert 3 to senepodine G (2) (six steps, 40% overall yield), and the stereospecific NaBH4 reduction of 2 to give cermizine C (1) (seven steps, 40% overall yield). 相似文献
86.
Grabowski SJ 《The journal of physical chemistry. A》2007,111(17):3387-3393
Pi-electrons of acetylene and sigma-electrons of molecular hydrogen were investigated as Lewis bases in different complexes. Hence high level ab initio calculations were performed up to the MP2/6-311++G(3df,3pd) level of approximation. It was found that species analyzed possess characteristics typical for H-bonded systems. The Bader theory was additionally applied; bond paths between proton and pi-electrons of acetylene or sigma-electrons of molecular hydrogen were detected with the corresponding bond critical points attributed to the proton-acceptor interactions. Numerous correlations between topological, geometrical and energetic parameters were also found. For example, the H...pi or H...sigma interaction is stronger for the shorter corresponding distance between the proton and the middle of C[triple bond]C or H-H bond. It is connected with the greater elongation of C[triple bond]C or H-H bonds and the greater transfer of electron charge from the Lewis base to the Lewis acid. 相似文献
87.
88.
89.
L. T. Demoranville D. L. Knies K. S. Grabowski A. C. Mignerey 《Journal of Radioanalytical and Nuclear Chemistry》2009,282(1):305-308
The Naval Research Laboratory’s Trace Element AMS system’s use of a Pretzel magnet as a recombinator and mass filter offers
a unique opportunity to study a new type of time-of-flight (TOF) spectrometry. Mass filtering prior to TOF analysis removes
extraneous species, shortening the analysis time for a single beam pulse, thereby improving the duty cycle. Time dilation
results from a longer flight path for a heavier mass in the Pretzel magnet. Computer TOF simulations of these factors and
the resulting impact on mass resolution for high mass atomic and molecular species are discussed. Initial measurements of
carbon and silicon to confirm the validity of the model are presented. 相似文献
90.
D. A. Garber M. Behar Z. W. Grabowski Wm. C. King 《Zeitschrift für Physik A Hadrons and Nuclei》1974,270(3):163-167
The iron-implantation-perturbed-angular-correlation technique (IMPACT) has been used to measure the Larmor precessions of the 328, 240, and 356 keV states of194Pt,195Pt, and196Pt nuclei, respectively, in ferromagnetic iron and cobalt hosts. The observed angular precessions in iron, corrected for the transient field effect, wereω τ 194(328)=0.103±0.006 rad,ω τ 195 (240)=0.142±0.012, andω τ 196(356)=0.084±0.010. For cobalt hosts, the observed Larmor precessions were ω τ194(328)=0.068±0.006, ω τ195(240)=0.096±0.012, andω τ 196(356)=0.057±0.013. Agreement between theg-factors obtained from the measurements in iron hosts and the measurements in cobalt hosts is very good, and a weighted average of the two measurements givesg 194(328)=0.349±0.031,g 195 (240)=0.136±0.013, andg 196(356)=0.329±0.039. 相似文献