Quantum Inverse Algorithm via Adaptive Variational Quantum Linear Solver: Applications to General Eigenstates

We propose a quantum inverse algorithm (QInverse) to directly determine general eigenstates by repeatedly applying the inverse power of a shifted Hamiltonian to an arbitrary initial state. To properly deal with the strongly entangled inverse power states and the resultant excited states, we solved the underlying linear equation, both variationally and adaptively, to obtain a faithful inverse power state with a shallow quantum circuit. QInverse is singularity-free and successfully obtains the target excited states with an energy closest to the shift ω, which is difficult to reach using variational methods. We also propose a subspace expansion approach to accelerate convergence and show that it is helpful to determine the two nearest eigenvalues when they are equally close to ω. These approaches were compared with the folded-spectrum method, which aims to generate excited states through variational optimization. It is shown that, whereas the folded-spectrum approach often fails to predict the target state by falling into a local minimum owing to its variational features, the success rate and accuracy of our algorithms are systematically improvable.

Improved Algorithms of Quantum Imaginary Time Evolution for Ground and Excited States of Molecular Systems

Quantum imaginary time evolution (QITE) is a recently proposed quantum-classical hybrid algorithm that is guaranteed to reach the lowest state of systems. In this study, we present several improvements on QITE, mainly focusing on molecular applications. We analyze the derivation of the underlying QITE equation order-by-order and suggest a modification that is theoretically well founded. Our results clearly indicate the soundness of the here-derived equation, enabling a better approximation of the imaginary time propagation by a unitary. We also discuss how to accurately estimate the norm of an imaginary-time-evolved state and applied it to excited-state calculations using the quantum Lanczos algorithm. Finally, we propose the folded-spectrum QITE scheme as a straightforward extension of QITE for general excited-state simulations. The effectiveness of all these developments is illustrated by simulations with or without noise effect, offering further insights into quantum algorithms for imaginary time evolution.

Binary dopant segregation enables hematite-based heterostructures for highly efficient solar H2O2 synthesis

Dopant segregation, frequently observed in ionic oxides, is useful for engineering materials and devices. However, due to the poor driving force for ion migration and/or the presence of substantial grain boundaries, dopants are mostly confined within a nanoscale region. Herein, we demonstrate that core–shell heterostructures are formed by oriented self-segregation using one-step thermal annealing of metal-doped hematite mesocrystals at relatively low temperatures in air. The sintering of highly ordered interfaces between the nanocrystal subunits inside the mesocrystal eliminates grain boundaries, leaving numerous oxygen vacancies in the bulk. This results in the efficient segregation of dopants (~90%) on the external surface, which forms their oxide overlayers. The optimized photoanode based on hematite mesocrystals with oxide overlayers containing Sn and Ti dopants realises high activity (~0.8 μmol min⁻¹ cm⁻²) and selectivity (~90%) for photoelectrochemical H₂O₂ production, which provides a wide range of application for the proposed concept.

Photoelectrochemical H₂O₂ production offers a renewable means for chemical synthesis, yet water oxidation to H₂O₂ remains a challenge. Here, authors prepare heterostructured, metal-doped hematite mesocrystals that show a high selectivity for photoelectrochemical H₂O₂ alongside H₂ production.

Software for the frontiers of quantum chemistry: An overview of developments in the Q-Chem 5 package

This article summarizes technical advances contained in the fifth major release of the Q-Chem quantum chemistry program package, covering developments since 2015. A comprehensive library of exchange-correlation functionals, along with a suite of correlated many-body methods, continues to be a hallmark of the Q-Chem software. The many-body methods include novel variants of both coupled-cluster and configuration-interaction approaches along with methods based on the algebraic diagrammatic construction and variational reduced density-matrix methods. Methods highlighted in Q-Chem 5 include a suite of tools for modeling core-level spectroscopy, methods for describing metastable resonances, methods for computing vibronic spectra, the nuclear-electronic orbital method, and several different energy decomposition analysis techniques. High-performance capabilities including multithreaded parallelism and support for calculations on graphics processing units are described. Q-Chem boasts a community of well over 100 active academic developers, and the continuing evolution of the software is supported by an "open teamware" model and an increasingly modular design.

Improved Description and Efficient Implementation of Spin-Projected Perturbation Theory for Practical Applications

In this study, we continue to develop the recently proposed second-order perturbation theory for the spin-projected Hartree-Fock method [Tsuchimochi, T.; Ten-no, S. L. J. Chem. Theory Comput. 2019, 15, 6688] in various aspects. A new, stable imaginary level-shift scheme is derived to obtain a well-conditioned equation, enabling a significantly faster convergence. To achieve a further speed-up, we propose a preconditioning scheme considering the pair character on a spin-projected basis. We also eliminate the computational memory bottleneck in solving the linear equation for large systems using a distributed memory parallel implementation. Finally, for the description of open-shell molecules, several modified zeroth-order Hamiltonians are introduced and tested using the Mn₂O₂(NHCHCO₂)₄ complex. These developments enable practical calculations of a second-order perturbation theory with improved accuracy at a reduced computational cost.

Extending spin-symmetry projected coupled-cluster to large model spaces using an iterative null-space projection technique

Recently, we introduced an orbital-invariant approximate coupled-cluster (CC) method in the spin-projection manifold. The multi-determinantal property of spin-projection means that the parametrization in the spin-extended CC (ECC) ansatz is nonorthogonal and overcomplete. Therefore, the linear dependencies must be removed by an orthogonalization procedure to obtain meaningful solutions. Multi-reference methods often achieve this by diagonalizing a metric of the equation system, but this is not feasible with ECC because of the enormous size of the metric, a consequence of the incomplete active space of the spin-projected Hartree-Fock reference. As a result, the applicability of ECC has been limited to small benchmark systems, for which the ansatz was shown to be superior to the configuration interaction and linearized approximations. In this article, we provide a solution to this problem that completely avoids the metric diagonalization by iteratively projecting out its null-space from the working equations. As the additional computational cost required for this iterative projection is only marginal, it greatly expands the application range of ECC. We demonstrate the potential of approximate ECC by studying the complete basis set limit of F₂ and transition metal complexes such as NiO, Mn₂ , and [Cu₂ O₂ ]²⁺ , which have all been hindered by the prohibitively large metric size. We also identify the potential inadequacy of the molecular orbitals given by spin-projected Hartree-Fock in some cases, and propose possible solutions. © 2018 Wiley Periodicals, Inc.

Orbital-invariant spin-extended approximate coupled-cluster for multi-reference systems

We present an approximate treatment of spin-extended coupled-cluster (ECC) based on the spin-projection of the broken-symmetry coupled-cluster (CC) ansatz. ECC completely eliminates the spin-contamination of unrestricted CC and is therefore expected to provide better descriptions of dynamical and static correlation effects, but introduces two distinct problems. The first issue is the emergence of non-terminating amplitude equations, which are caused by the de-excitation effects inherent in symmetry projection operators. In this study, we take a minimalist approach and truncate the Taylor series of the exponential ansatz at a certain order such that the approximation safely recovers the traditional CC without spin-projection. The second issue is that the nonlinear equations of ECC become underdetermined, although consistent, yielding an infinitude of solutions. This problem arises because of the redundancies in the excitation manifold, as is common in other multi-reference approaches. We remove the linear dependencies in ECC by employing an orthogonal projection manifold. We also propose an efficient solver for our method, in which the components are usually sparse but not diagonal-dominant. It is shown that our approach is rigorously orbital-invariant and provides more accurate results than its configuration interaction and linearized CC analogues for chemical systems.

What can density functional theory tell us about artificial catalytic water splitting?

Water splitting by artificial catalysts is a critical process in the production of hydrogen gas as an alternative fuel. In this paper, we examine the essential role of theoretical calculations, with particular focus on density functional theory (DFT), in understanding the water-splitting reaction on these catalysts. First, we present an overview of DFT thermochemical calculations on water-splitting catalysts, addressing how these calculations are adapted to condensed phases and room temperature. We show how DFT-derived chemical descriptors of reactivity can be surprisingly good estimators for reactive trends in water-splitting catalysts. Using this concept, we recover trends for bulk catalysts using simple model complexes for at least the first-row transition-metal oxides. Then, using the CoPi cobalt oxide catalyst as a case study, we examine the usefulness of simulation for predicting the kinetics of water splitting. We demonstrate that the appropriate treatment of solvent effects is critical for computing accurate redox potentials with DFT, which, in turn, determine the rate-limiting steps and electrochemical overpotentials. Finally, we examine the ability of DFT to predict mechanism, using ruthenium complexes as a focal point for discussion. Our discussion is intended to provide an overview of the current strengths and weaknesses of the state-of-the-art DFT methodologies for condensed-phase molecular simulation involving transition metals and also to guide future experiments and computations toward the understanding and development of novel water-splitting catalysts.

Influence of third molar space on angulation and dental arch crowding

The influence of the third molars on mandibular incisor crowding has been extensively studied but remains controversial. The purpose of this study was to ascertain whether, in Mongolian subjects, the lower third molar can affect anterior crowding and/or the inclination of teeth in the lower lateral segments. Panoramic radiographs, 45° oblique cephalograms, and dental casts were taken from Mongolian subjects (age range 18.3-24.1 years, mean 21.0 years) exhibiting impaction of all four third molars and an Angle Class I molar relationship. The Ganss ratio was calculated using panoramic radiographs, whereas the gonial angle and angulation of lower canines, premolars and molars were measured using 45° oblique cephalograms. Little's index of irregularity was calculated using dental casts. Significant relationships between the angulation of the third and second molars and between the first molars and second premolars were found. Conversely, there was no significant correlation between the angulation of third molars, first premolars and canines. The Ganss ratio calculations showed that the lower first and second molars and the second premolars inclined mesially if there was insufficient space for the lower third molars. However, there was no significant correlation between Little's index of irregularity and third molar angulation. Furthermore, although the third molar influences the lateral segments, no obvious relationship between the third molar and anterior crowding was observed. Therefore, the angulation of the third molar appears not to cause anterior crowding.

Y-chromosomal STR haplotype in the Japanese population

Allele and haplotype frequencies of seven Y-chromosome STR loci from samples of 108 unrelated Japanese males living in Aichi Prefecture.

[A case of identification of two persons from heavily burned teeth by age estimation]

A man murdered his two daughters, one five years and two months old and one seven months old. He placed them into a 750 degrees C aluminum liquefying furnace. Teeth and many fragments of the severely burned bones were recovered. However, at first, the bone fragments did not offer proof that two children were put into the furnace. The age estimation of the teeth burned in liquefied aluminum was carried out based on the maturity of the teeth and the degree of absorption of deciduous teeth roots. As a result from the admixture of permanent teeth and deciduous teeth, we presumed them to be derived from more than one person.

[Biochemical and morphological studies on soft tissues in hip osteoarthrosis]

To investigate the pathogenesis of osteoarthrosis, we have performed biochemical and morphological studies, other than roentgenological examination, on the soft tissues. Biochemical analyses of collagen were performed on muscles (gluteus medius) in normal and in pathological cases. In the terminal stage of osteoarthrosis, we observed more immature collagen fibers in muscles, than in normal cases. In the preosteoarthrosis stage, immature collagen formation was inconsistent with various degrees of immaturity observed. Morphologically, irregularity in the muscle fibers and interfascicular-fibrosis was observed in the gluteus medius only at the terminal stage but not at the preosteoarthrosis stage. In some cases, we observed a predominance and/or grouping of type 1 fibers. Among the 20 cases with preosteoarthrosis, 3 cases (15%) showed marked biochemical changes in both quantity and quality of collagen fibers in the gluteus medius, as compared with cases at the terminal stage. These findings may be valuable in studying the onset and development of the pathophysiology of osteoarthrosis.

Induction of differentiation and growth suppression of myeloid leukemia cells by sera of patients with hematological disorders

In severe infection, the host responds to foreign agents and produces cytokines to activate lymphocytes and macrophages. Some of these cytokines can modulate growth and differentiation of myeloid leukemia cells. We examined differentiation-inducing activities in the sera from 9 patients with leukemia or lymphoma. These results indicate that some sera from infected patients, even with acute leukemia, have significant differentiation-inducing activities on both mouse and human leukemia cells, and that cytokines having differentiation-inducing activities varied for different specimens.

Fine needle aspiration cytology of clear cell sarcoma. Report of a case with immunocytochemical, immunohistochemical and ultrastructural studies

Cytologic findings of clear cell sarcoma obtained by fine needle aspiration (FNA) of a tumor are described. The tumor probably originated in the retroperitoneal tissue, and the diagnosis was confirmed histologically by open biopsy. Percutaneous needle aspirates of the intraabdominal tumor and touch preparations obtained from the open biopsy specimen revealed numerous atypical cells with an extremely hyperchromatic nucleus, prominent nucleoli and clear cytoplasm. The cytoplasm was rich in glycogen. The immunocytochemical technique demonstrated S-100 protein and neuron-specific enolase in the cytoplasm, both of which were exhibited also in the histologic specimen. Clear cell sarcoma is a rare tumor of soft tissue, and to our knowledge, detailed cytologic appearances of this tumor obtained by FNA have not been reported. In addition, the present tumor was unique in location. It is possible to diagnose clear cell sarcoma accurately on an FNA cytologic specimen if the periodic acid-Schiff stain and immunocytochemical technique are utilized in addition to the routine Papanicolaou method.

[Malignant lymphoma occurring subsequent to autoimmune disease]

The authors report six cases of non-Hodgkin's lymphoma (NHL) (3B-cell type, one T-cell type, one non-T non-B cell type, one unclassified type) occurring subsequently to autoimmune diseases. The patients were females aged 43 to 70 (median 61). Rheumatoid arthritis was most frequent as the preceding autoimmune disease, and the intervals from the onset of an autoimmune disease to that of NHL were 10 to 36 years (median 20). Polyclonal hypergammaglobulinemia was seen in 4 cases, lymphocytopenia in 3 cases, and conversion to negative PPD reaction in 2 cases. Only one patient had been given corticosteroids, and immunosuppressive agents may not contribute much to the development of lymphoma in patients with autoimmune diseases.

[An 8; 21 chromosome translocation associated leukemia presenting with large intestinal granulocytic sarcoma: a report of two cases]

Two patients of acute myelogenous leukemia (AML) presented with a large intestinal tumor and related symptoms. They had a tumor in the rectum or the ascending colon. Bone marrow cells obtained from both patients showed a karyotype with t(8;21). Chromosomal findings in the former patient has already been reported in detail (Am J Hematol 4, 273, 1978). These findings and reports in the literature indicate that large intestinal tumor may not be rare in AML with an 8;21 translocation. Complete remission was achieved after chemotherapy, when their intestinal tumors disappeared.

Posttransfusion fulminant hepatitis B associated with precore-defective HBV mutants

Fulminant hepatitis B developed in 8 recipients of blood units without detectable hepatitis B surface antigen on routine screening. All 124 hepatitis B virus (HBV) DNA clones propagated from their sera possessed defects in the precore region. A point mutation from guanine to adenine at nucleotide 83, converting codon 28 for tryptophan (TGG) to a stop codon (TAG), was the commonest, and it was found in all 113 clones from 7 cases. The remaining case displayed 1 clone with this point mutation and 10 clones with an insertion of 2 base pairs after nucleotide 26. Antibody to hepatitis B core antigen (anti-HBc) was detected in a high titer in 1 of 10 pilot plasma samples of blood units transfused to this case. HBV DNA clones propagated from it exhibited the same precore-region defects as those from the recipient. On the basis of these results HBV mutants, defective in the precore region, would appear to be responsible for posttransfusion fulminant hepatitis B, and the exclusion of blood units with high-titered anti-HBc would be efficacious in preventing it.

Pheochromocytoma with renal artery stenosis and high plasma renin activity

An unusual case of pheochromocytoma is described in this communication. Besides a chain of typical clinical pictures and laboratory findings which suggested a catecholamine-producing tumor, the left renal artery stenosis was demonstrated by an aortography and the plasma renin activity was consistently elevated. Surgery revealed the left renal artery was embedded in the tumor mass, originated from the left adrenal gland, resulting in a high degree of constricture of the vessel. Following the removal of the tumor, blood pressure immediately returned to normal, however, plasma renin activity remained elevated as long as 9 months of the follow-up study. The second aortography performed 14 months after the operation failed to demonstrate the left renal artery stenosis and subsequent studies revealed that plasma renin activity was gradually declining to upper normal levels. It is suggested that an excess of catecholamines secreted by the tumor was responsible for hypertension in this case, and that another factor, probably renal artery stenosis, was involved in the elevation of plasma renin activity, although this high renin activity was maintained for more than 9 months following the tumor extirpation.