•We propose an efficient extrapolation scheme for solid-state NMR calculations.•The method combines quantum chemical and solid-state physical NMR approaches.•Our scheme reduces the disadvantages of both approaches.•The method yields accurate solid-state NMR properties.Conventional quantum chemical and solid-state physical approaches include several problems to accurately calculate solid-state nuclear magnetic resonance (NMR) properties. We propose a reliable computational scheme for solid-state NMR chemical shifts using an extrapolation scheme that retains the advantages of these approaches but reduces their disadvantages. Our scheme can satisfactorily yield solid-state NMR magnetic shielding constants. The estimated values have only a small dependence on the low-level density functional theory calculation with the extrapolation scheme. Thus, our approach is efficient because the rough calculation can be performed in the extrapolation scheme.Download high-res image (114KB)Download full-size image

Two-component relativistic equation-of-motion coupled-cluster methods are developed and implemented. Scalar-relativistic and spin–orbit effects are taken into account through a two-component scheme in both Hartree–Fock and correlation calculations. Excitation energies and spin–orbit splittings of atoms and diatomic molecules, and ionization potentials of OsO4 are reported. The advantage of the present two-component scheme is illustrated particularly for heavy-element systems.

We theoretically investigated the physical properties, including the frontier orbital and excitation energies, for thiophene-based semiconducting polymers composed of donor and acceptor units. Orbital analysis revealed that remarkably different behaviors of frontier orbital energies with respect to the degree of polymerization stems from the distribution of the frontier orbitals, which is insightful information for controlling the ionization potentials and electron affinities of semiconducting polymers. We also successfully estimated the frontier orbital energies of the polymers through a simple Hückel theory-based analytical model parametrized from calculations of relatively small oligomers. This simple model allows us to predict the highest occupied molecular orbital–lowest unoccupied molecular orbital gaps of a polymer at a low computational cost. The simulated absorption spectra of the thiophene-based semiconducting polymers were compared with the experimental spectra. The theoretically designed polymers were also investigated in terms of their frontier orbital energies and absorption spectra toward synthesizing promising polymers.

A new algorithm for massively parallel calculations of electron correlation energy of large molecules based on the resolution of identity second-order Møller–Plesset perturbation (RI-MP2) technique is developed and implemented into the quantum chemistry software NTChem. In this algorithm, a Message Passing Interface (MPI) and Open Multi-Processing (OpenMP) hybrid parallel programming model is applied to attain efficient parallel performance on massively parallel supercomputers. An in-core storage scheme of intermediate data of three-center electron repulsion integrals utilizing the distributed memory is developed to eliminate input/output (I/O) overhead. The parallel performance of the algorithm is tested on massively parallel supercomputers such as the K computer (using up to 45 992 central processing unit (CPU) cores) and a commodity Intel Xeon cluster (using up to 8192 CPU cores). The parallel RI-MP2/cc-pVTZ calculation of two-layer nanographene sheets (C150H30)2 (number of atomic orbitals is 9640) is performed using 8991 node and 71 288 CPU cores of the K computer.