Hiromi Nakai

In addition to diastolic dysfunction, subclinical LV longitudinal dysfunction is preferentially and frequently observed in asymptomatic diabetes patients with normal LVEF. The decrease in LS correlated with duration of diabetes. 2DSTE has the potential for detecting subclinical LV systolic dysfunction and might provide useful information of the risk stratification in an asymptomatic diabetic population.

The divide-and-conquer (DC) method, which is one of the linear-scaling methods avoiding explicit diagonalization of the Fock matrix, has been applied mainly to pure density functional theory (DFT) or semiempirical molecular orbital calculations so far. The present study applies the DC method to such calculations including the Hartree-Fock (HF) exchange terms as the HF and hybrid HF/DFT. Reliability of the DC-HF and DC-hybrid HF/DFT is found to be strongly dependent on the cut-off radius, which d

Abstract We develop a simultaneous determination method of nuclear and electronic wave functions without the Born–Oppenheimer approximation. We examine two expanding methods, namely, molecular orbital (MO)‐type and valence bond (VB)‐type expansions for a nuclear orbital, which is a one‐particle wave function of a nucleus. The VB‐type expansion is shown to be more accurate than the MO‐type one because of the local nature of the nuclei. We also investigate the basis function expansion of the nucle

Abstract We review a recent development in a rigorous non‐Born–Oppenheimer method, i.e., nuclear orbital plus molecular orbital (NOMO) method, which determines the nuclear and electronic wave functions simultaneously. The NOMO theory is an exact theory for the non‐BO problem in principle; for example, full‐configuration interaction formulation for a complete configuration space. Hartree–Fock (HF) equations for NOs and MOs are derived for practical calculations. The usage of Gaussian basis functi

We have investigated the many-body effects in a molecular theory to determine simultaneously nuclear and electronic wave functions without the Born–Oppenheimer (BO) approximation. We first apply the many-body perturbation theory using the electron–nucleus and nucleus–nucleus interactions to the non-BO theory and show the importance of the electron–nucleus correlation rather than the nucleus–nucleus one. We next combine the non-BO theory with the coupled cluster double and Brueckner double method

The linear-scaling divide-and-conquer (DC) quantum chemical methodology is applied to the density-functional tight-binding (DFTB) theory to develop a massively parallel program that achieves on-the-fly molecular reaction dynamics simulations of huge systems from scratch. The functions to perform large scale geometry optimization and molecular dynamics with DC-DFTB potential energy surface are implemented to the program called DC-DFTB-K. A novel interpolation-based algorithm is developed for para

Superconcentrated electrolyte solutions are receiving increasing attention as a novel class of liquid electrolyte for secondary batteries because of their unusual and favorable characteristics, which arise from a unique solution structure with a very small number of free solvent molecules. The present theoretical study investigates the concentration dependence of the structural and dynamical properties of these electrolyte solutions for Na-ion batteries using large-scale quantum molecular dynami

Dcdftbmd is a Fortran 90/95 program that enables efficient quantum mechanical molecular dynamics (MD) simulations using divide-and-conquer density functional tight-binding (DC-DFTB) method. Based on the remarkable performance of previous massively parallel DC-DFTB energy and gradient calculations for huge systems, the code has been specialized to MD simulations. Recent implementations and modifications including DFTB extensions, improved computational speed in the DC-DFTB computational steps, al

The nuclear orbital plus molecular orbital (NOMO) theory was developed in order to determine the nonadiabatic nuclear and electronic wave functions. This study presents a formulation to remove the contamination of rotational motion as well as translational motion in the NOMO theory. We have formulated the translation- and rotation-free (TRF)-NOMO theory by introducing the TRF Hamiltonian. The principal moment of inertia, which is the denominator in the rotational Hamiltonian, is expanded in a Ta

The symmetry adapted cluster (SAC) and SAC-configuration interaction (SAC-CI) theories are applied to the calculations of the ground and excited states of MnO−4. With the use of three different active spaces, we examine the convergence of the results. Electron correlations work to relax charge polarizations of the Mn–O bonds in the ground state. The experimental spectrum of MnO−4 is well reproduced by the present calculations. All of the observed peaks are assigned to the electronic allowed tran