In the case that the parameters to describe the force field, such as bond angles and charges, cannot be added to the library of a molecular dynamics (MD) simulation, self-development of the force field should be considered by performing quantum mechanics calculations and/or utilizing an automatic parameter generation tool. However, these techniques are not suitable for macromolecules with a large number of atoms. Typically, the force field of an oligomer containing three unit structures (a unit at both ends and a repeating unit at the center) is calculated and converted to polymer form (both ends + central part × n). Considering this, we recently developed the program o2p, which is a semi-automated program designed to set up the force field for polymers with repeating structures. However, it is difficult to apply this method to macromolecules with complex repeating structures. Thus, in this project, we developed PolyParGen, a new open-source automatic force field generation program for Gromacs that can relatively easily and reliably simulate the MD of complex macromolecules. The proposed program (1) divides the structure of the polymer into substructures with a number of atoms within the limit of the handling size for the automatic parameter generation tool program; then, (2) acquire the parameters for each divided substructure, and finally, (3) combine the parameters of these substructures to obtain the parameters for the whole polymer. By automating these processes, it is possible to acquire a parameter of a polymer having complicated structures. This program was evaluated by simulating the polymers P3EHT and F-P3EHT in chloroform. In agreement with previous reports, fluorination was found to cause F-P3EHT to adopt an extended structure, thereby indicating the effectiveness of the proposed program.

A novel protic ionic liquid ethylmethylpropylammonium nonafluorobutanesulfonate ([empa][NfO]) was found to exhibit hydrophobicity, high ionic conductivity, and facile electroactivity toward hydrogen oxidation and oxygen reduction reactions; these properties make it a suitable electrolyte for nonhumidified intermediate-temperature fuel cells.

Structural specificity including dynamic behavior and stable conformations in the bulk phase of diethylmethylammonium trifluoromethanesulfonate [dema][TfOH], which is assumed to be a prominent ionic liquid electrolyte for non-humidified intermediate temperature fuel cells, have been investigated by 1H NMR, IR spectroscopic analyses, and molecular dynamics (MD) simulation. It is found that an N–H proton in [dema][TfOH] is an exchangeable mobile proton which can be substituted by D2O, and free rotation around the N–C bond in the ethyl side chain of the ammonium cation is retarded by ionic interactions between the cations and anions, therefore the methylene protons in the ethyl side chain are unisochronous. In addition, the rotational barrier of this N–C bond was observed to be 71 kJ mol−1, comparable to the barrier height of the amide N–C bond (which is well-known to have partial double bond character) from temperature-dependent NMR experiments by monitoring the peak-shape changes of methylene protons in the ethyl side chain of the ammonium cation. The bulk-phase structure of [dema][TfOH] was calculated by MD simulations on the basis of the OPLS-AA force field, and the evaluated structure was consistent with those of experimental results. Thus, IR spectrum frequency of the N–H proton, and the 1H NMR chemical shift values could be rationally assigned on the basis of the theoretically evaluated structures in the bulk phase.

Ferroelectric mesocrystals of Bi0.5Na0.5TiO3 (BNT) with [100]-crystal-axis orientation were successfully prepared using a topotactic structural transformation process from a layered titanate H1.07Ti1.73O4·nH2O (HTO). The formation reactions of BNT mesocrystals in HTO-Bi2O3-Na2CO3 and HTO-TiO2-Bi2O3-Na2CO3 reaction systems and their nanostructures were studied by XRD, FE-SEM, TEM, SAED, and EDS, and the reaction mechanisms were given. The BNT mesocrystals are formed by a topotactic structural transformation mechanism in the HTO-Bi2O3-Na2CO3 reaction system and by a combination mechanism of the topotactic structural transformation and epitaxial crystal growth in the HTO-TiO2-Bi2O3-Na2CO3 reaction system, respectively. The BNT mesocrystals prepared by these methods are constructed from [100]-oriented BNT nanocrystals. Furthermore, these reaction systems were successfully applied to the fabrication of [100]-oriented BNT ferroelectric ceramic materials. A BNT ceramic material with a high degree of orientation, high relative density, and small grain size was achieved.

We investigated a V-based electrode for the realization of low ohmic-contact resistivity in n-type AlGaN with a high AlN molar fraction characterized by the circular transmission line model. The contact resistivity of n-type Al0.62Ga0.38N prepared using the V/Al/Ni/Au electrode reached 1.13 × 10−6 Ω cm2. Using this electrode, we also demonstrated the fabrication of UV light-emitting diodes (LEDs) with an emission wavelength of approximately 300 nm. An operating voltage of LED prepared using a V/Al/Ni/Au electrode was 1.6 V lower at 100 mA current injection than that prepared using a Ti/Al/Ti/Au electrode, with a specific contact resistance of approximately 2.36 × 10−4 Ω cm2 for n-type Al0.62Ga0.38N.