Tensor factorizations of local second-order M{\o}ller Plesset theory

Efficient electronic structure methods can be built around efficient tensor representations of the wavefunction. Here we describe a general view of tensor factorization for the compact representation of electronic wavefunctions. We use these ideas to construct low-complexity representations of the doubles amplitudes in local second order M{\o}ller-Plesset perturbation theory. We introduce two approximations - the direct orbital specific virtual approximation and the full orbital specific virtual approximation. In these approximations, each occupied orbital is associated with a small set of correlating virtual orbitals. Conceptually, the representation lies between the projected atomic orbital representation in Pulay-Saeb{\o} local correlation theories and pair natural orbital correlation theories. We have tested the orbital specific virtual approximations on a variety of systems and properties including total energies, reaction energies, and potential energy curves. Compared to the Pulay-Saeb{\o} ansatz, we find that these approximations exhibit favourable accuracy and computational times, while yielding smooth potential energy curves

Continuous measurement of heart rate variability following carbon dioxide pneumoperitoneum during nitrous oxide/sevoflurane anaesthesia

Background: Previous studies of autonomic nervous system activity through analysis of heart rate variability (HRV) have demonstrated increased sympathetic activity during positive-pressure pneumoperitoneum. We employed an online, continuous method for rapid HRV analysis (MemCalc™, Tarawa, Suwa Trust, Tokyo, Japan) to demonstrate rapid changes in autonomic nervous system during pneumoperitoneum for laparoscopy. Method: The powers of low-frequency (LF) (0.04-0.15 Hz) and high-frequency (HF) (0.15-0.4 Hz) components of HRV in 20 healthy adult patients were monitored under sevoflurane anaesthesia for 10 minutes after the initiation of carbon dioxide pneumoperitoneum at 10 mmHg. Results: Heart rate increased promptly, but transiently, just after peritoneal insufflation. At that time, the ratio between the LF and HF components increased on HRV. Similar, but small, changes occurred following head-up positioning. Conclusion: By monitoring HRV continuously, we have demonstrated that the change in autonomic nervous system balance induced by peritoneal insufflation was prompt and transient. The change in autonomic nervous system activity could have been due to increased sympathetic activity, reduced vagal activity, or both.Keywords: heart rate variability; positive pressure pneumoperitoneum; continuous monitorin

Au25 cluster-loaded SrTiO3 water-splitting photocatalyst; preparation and elucidation of the effect of cocatalyst refinement on photocatalytic activity

Water-splitting photocatalysts have attracted much attention for decades as materials to produce clean and renewable hydrogen (H2) as a fuel. In this study, we succeeded in precisely loading ultrafine gold cocatalyst particles (Au25 clusters) on the water-splitting photocatalyst SrTiO3 using glutathionate-protected Au25 clusters as a precursor. Photocatalysis experiments using the obtained photocatalyst revealed that the ultraminiaturization of the Au cocatalyst on SrTiO3 improves its water-splitting activity. The main reason for this improvement was attributed to the acceleration of the H2-evolution reaction caused by the ultra-miniaturization of the cocatalyst. This effect of refining the cocatalyst differs from that of Au-loaded BaLa4Ti4O15. These results demonstrate that the effect of ultra-miniaturization of the cocatalyst on photocatalytic activity varies depending on the photocatalyst

Controlled Thiolate-Protected Gold and Alloy Clusters

Small metal clusters exhibit physical and chemical properties that differ substantially from those of corresponding bulk metals. Furthermore, the properties of clusters vary greatly depending on the number of constituent atoms. Metal clusters with these characteristics currently attract great attention in a wide range of fields as new nanoscale functional materials. In recent years, the techniques to precisely synthesize metal clusters protected with organic ligands and polymers with atomic precision have advanced dramatically. In addition, substantial knowledge of the size-specific physical/chemical properties exhibited by these metal clusters has been accumulated. In this chapter, we describe the precise synthesis methods of the most studied thiolate (SR)-protected gold clusters Aun(SR)m and their heteroatom-substituted clusters (alloy clusters)

Multireference quantum chemistry through a joint density matrix renormalization group and canonical transformation theory

We describe the joint application of the density matrix renormalization group and canonical transformation theory to multireference quantum chemistry. The density matrix renormalization group provides the ability to describe static correlation in large active spaces, while the canonical transformation theory provides a high-order description of the dynamic correlation effects. We demonstrate the joint theory in two benchmark systems designed to test the dynamic and static correlation capabilities of the methods, namely, (i) total correlation energies in long polyenes and (ii) the isomerization curve of the [Cu2O2]^(2+) core. The largest complete active spaces and atomic orbital basis sets treated by the joint DMRG-CT theory in these systems correspond to a (24e,24o) active space and 268 atomic orbitals in the polyenes and a (28e,32o) active space and 278 atomic orbitals in [Cu2O2]^(2+)