A program written in JAVA language was developed for the virtual electrochemical measurement of a modified electrode with a finite diffusion thickness, e.g., an electrode coated with polymer film in which functional molecules were dispersed. This program, called ES-2, can simulate cyclic voltammetry and potential-step chronoamperospectrometry by considering the rate of charge injection from the electrode to the functional molecule and the diffusion of charge. The results are shown by a voltammogram (I-V curve), and concentration distribution in the layer at a series of voltages at cyclic voltammogram mode, I-t curve, and time dependence of concentration distribution in the layer at potential step mode and a text of current values, the fraction of the oxidized molecules (RCT) and parameters used for the simulation in both modes. A dynamic textbook of electrochemistry can be constructed by this program combined with HTML text.
A virtual bipolar photogalvanic cell was developed using Visual Basic. On the basis of the simulation, it is indicated that the charge separation (kd) and the charge recombination (kr) rate constants can be estimated using the photocurrent response. The thickness of the charge separation region can be anticipated by photocurrent response at various layer thicknesses. The increase in diffusion coefficients raises the short-circuit photocurrent to enhance the performance of the photogalvanic cell. An actual device was fabricated using tris(bipyridine)ruthenium(II) complex ([Ru(bpy)32+]) as a sensitizer and Prussian Blue as a mediator. This device worked as a photogalvanic cell: short-circuit photocurrent (JSC), 2.3μA/cm2; open-circuit photovoltage (VOC), 0.118V; fill-factor, 20.5 %. It was shown from the action spectrum that electrons are transferred from [Ru(bpy)32+*] to Prussian Blue. The charge separation and the recombination rate constants were estimated, using the virtual device, to be 5 × 102 mol-1cm3s-1 and 6 × 109 mol-1cm3s-1, respectively.
We study the parallel processing environment using the MPI/LAM message passenger. We perform ab initio crystal orbital calculations of one-dimensional polymers using parallel processing. The personal computer cluster of eight dual CPU motherboards with Intel Pentium III 450MHz (total 16 CPU) is connected to a 100BaseT ethernet switch. The calculation on poly-tetrafluoro-ethylene (C2F4)x shows that the wall clock by 8 CPU is 6.27 times faster than that by the single CPU. The wall clock by 16 CPU, however, remains just 6.96 times faster than that by single CPU, which should be attributed to the inefficiency of the dual CPU motherboard on the I/O wait time and the network wait time. The calculation on poly-(para-phenylene sulfide) (C6H4SC6H4S)x shows that the wall clock by 8 CPU becomes about 20 times faster than that by the single CPU. This is enabled by the fact that the total system memory becomes greater than the temporary file of two electron integrals, which eliminates the access to the hard disk and I/O wait time. These results show the parallel processing of the electronic structure calculations on the one-dimensional polymers to be very effective in terms of the wall clock.
A computer-aided-education system available on the World Wide Web (WWW) for studying polyhedra was developed. The system has the following characteristics: easy operation by the use of a mouse and ample menu icons, and potential transferability for extension and development in various fields, such as mathematics, chemistry, architecture, and industrial design. Suggested examples of the usage of this system are given.
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