Self-Consistent Tensor Product Variational Approximation for 3D Classical Models

We propose a numerical variational method for three-dimensional (3D) classical lattice models. We construct the variational state as a product of local tensors, and improve it by use of the corner transfer matrix renormalization group (CTMRG), which is a variant of the density matrix renormalization group (DMRG) applied to 2D classical systems. Numerical efficiency of this approximation is investigated through trial applications to the 3D Ising model and the 3D 3-state Potts model.Comment: 12 pages, 6 figure

Microstructure and mechanical properties of hip-consolidated Rene 95 powders

The effects of heat-treatments on the microstructure of P/M Rene 95 (a nickel-based powder metal), consolidated by the hot-isostatic pressing (HIP), were examined. The microstructure of as-HIP'd specimen was characterized by highly serrated grain boundaries. Mechanical tests and microstructural observations reveal that the serrated grain boundaries improved ductility at both room and elevated temperatures by retarding crack propagation along grain boundaries

Numerical Latent Heat Observation of the q=5 Potts Model

Site energy of the five-state ferromagnetic Potts model is numerically calculated at the first-order transition temperature using corner transfer matrix renormalization group (CTMRG) method. The calculated energy of the disordered phase $U^{+}$ is clearly different from that of the ordered phase $U^{-}$. The obtained latent heat $L = U^{-} - U^{+}$ is 0.027, which quantitatively agrees with the exact solution.Comment: 2 pages, Latex(JPSJ style files are included), 2 ps figures, submitted to J. Phys. Soc. Jpn.(short note

The Density Matrix Renormalization Group technique with periodic boundary conditions

The Density Matrix Renormalization Group (DMRG) method with periodic boundary conditions is introduced for two dimensional classical spin models. It is shown that this method is more suitable for derivation of the properties of infinite 2D systems than the DMRG with open boundary conditions despite the latter describes much better strips of finite width. For calculation at criticality, phenomenological renormalization at finite strips is used together with a criterion for optimum strip width for a given order of approximation. For this width the critical temperature of 2D Ising model is estimated with seven-digit accuracy for not too large order of approximation. Similar precision is reached for critical indices. These results exceed the accuracy of similar calculations for DMRG with open boundary conditions by several orders of magnitude.Comment: REVTeX format contains 8 pages and 6 figures, submitted to Phys. Rev.

Polymorphisms in the 5′-UTR of PTEN and other gene polymorphisms in normal Japanese individuals

Polymorphisms are distributed differently in populations, including those of regions, ethnic groups, and diseased patients. In order to investigate variation in nucleotide sequences in normal individuals, we isolated genomic DNA from the blood of healthy Japanese individuals and sequenced the 5'-untranslated region (5'- UTR) of the phosphatase and tensin homolog deleted on chromosome 10 (PTEN) gene and the gene promoter, intron, and exon nucleotides of p53, p14ARF, murine double minute 2 (MDM2), and the β2- and β3-adrenoceptor (-AR). We found polymorphisms in these regions, including a deletion at positions –465 to –463 and a substitution at position –404 in PTEN and a substitution at position –4924 in p14ARF, in normal individuals. Individuals with or without the PTEN polymorphism harbored a different distribution of polymorphisms, including simultaneous alterations in nucleotides of p53, MDM2, and β3-AR, and also harbored some polymorphic nucleotides located in the same set of associatively altered nucleotides. Our results show that multiple nucleotides, including the PTEN nucleotides, are altered in normal Japanese individuals and provide useful information for genotyping studies in individuals and populations.Полиморфизмы широко распространены в популяциях, включая регионы, этнические группы и больных пациентов. Для исследования изменчивости нуклеотидных последовательностей у нормальных индивидов , мы выделили геномную ДНК из крови здоровых японцев и секвенировали 5′-нетранслируемый участок (5′-UTR) гена фосфатазы и гомолога тензина (PTEN), промоторные последовательности, интроны и экзоны генов p53 и p14ARF, ингибитора супрессора опухолевого роста p53 (MDM2) и генов β2- and β3-адренореце (-AR). Мы обнаружили полиморфизм по этим участкам, включая делецию в положении с −465 to −463 и замену в положении −404 в PTEN и замену в положении −4924 в p14ARF у нормальных индивидов. Индивиды с и без полиморфизма PTEN имели различное распределение полиморфизма, включая одновременные изменения в нуклеотидах p53, MDM2 и 3-AR, и также имели полиморфные нуклеотиды, локализованные в том же наборе совместно измененных нуклеотидов. Наши результаты показывают, что множественные нуклеотиды, включая нуклеотиды PTEN, изменены у нормальных японских индивидов и дают полезную информацию для исследований по генотипированию индивидов и популяций

Incommensurate structures studied by a modified Density Matrix Renormalization Group Method

A modified density matrix renormalization group (DMRG) method is introduced and applied to classical two-dimensional models: the anisotropic triangular nearest- neighbor Ising (ATNNI) model and the anisotropic triangular next-nearest-neighbor Ising (ANNNI) model. Phase diagrams of both models have complex structures and exhibit incommensurate phases. It was found that the incommensurate phase completely separates the disordered phase from one of the commensurate phases, i. e. the non-existence of the Lifshitz point in phase diagrams of both models was confirmed.Comment: 14 pages, 14 figures included in text, LaTeX2e, submitted to PRB, presented at MECO'24 1999 (Wittenberg, Germany

Macroscopic nucleation phenomena in continuum media with long-range interactions

Nucleation, commonly associated with discontinuous transformations between metastable and stable phases, is crucial in fields as diverse as atmospheric science and nanoscale electronics. Traditionally, it is considered a microscopic process (at most nano-meter), implying the formation of a microscopic nucleus of the stable phase. Here we show for the first time, that considering long-range interactions mediated by elastic distortions, nucleation can be a macroscopic process, with the size of the critical nucleus proportional to the total system size. This provides a new concept of "macroscopic barrier-crossing nucleation". We demonstrate the effect in molecular dynamics simulations of a model spin-crossover system with two molecular states of different sizes, causing elastic distortions.Comment: 12 pages, 4 figures. Supplementary information accompanies this paper at http://www.nature.com/scientificreport