Abstract: An organic nonlinear optical material comprising a compound having the iodonium salt structure represented by the general formula (I): ##STR1## wherein .pi..sub.1 to .pi..sub.n are the same or different and each is an atomic group having .pi. electron, I.sub.1 to I.sub.n-1 are an iodonium cation, A.sub.1 to A.sub.n-1 are the same or different and each is a counter anion for the iodonium cation, R.sup.1 and R.sup.2 are the same or different and each is a hydrogen atom or an electron donative group, and n is an integer of 2 to 4. The material has large nonlinear optical constants and shows no light absorption in the visible light region.

Abstract: A simulation method and design systems are provided for simulating and analyzing the properties of a periodically structured material such as a semiconductor or a superconductor to develop a novel periodically structured material. In the simulation method of the present invention, an overlap integral between Bloch functions, .psi..sub.m (k.sub.A) and .psi..sub.i (k.sub.B), for two adjacent wave number vectors, k.sub.A and k.sub.B, in Brillouin zone is found as S.sub.im =<.psi..sub.i (k.sub.B).vertline..psi..sub.m (k.sub.A)> whereby a matching degree in terms of symmetrical nature of the Bloch functions, .psi..sub.m (k.sub.A) and .psi..sub.i (k.sub.B), can be quantitatively estimated. Accordingly, if the band array operation matrix, ##EQU1## is diagonalized to find an eigenvalue, .gamma..sub.p and an eigenvector, U.sub.np, then there can be found from .gamma..sub.p and U.sub.np the Bloch functions in a one-to-one relation with two adjacent wave number vectors, k.sub.A and k.sub.

Abstract: A design system is provided for simulating and analyzing the properties of a periodically structured material such as a semiconductor or a superconductor to develop a novel periodically structured material. In the design system of the present invention, an overlap integral between Bloch functions, .psi..sub.m (k.sub.A) and .psi..sub.i (k.sub.B), for two adjacent wave number vectors, k.sub.A and k.sub.B, in Brillouin zone is found as S.sub.im =<.psi..sub.i (k.sub.B).vertline..psi..sub.m (k.sub.A)> whereby a matching degree in terms of symmetrical nature of the Bloch functions, .psi..sub.m (k.sub.A) and .psi..sub.i (k.sub.B), can be quantitatively estimated. Accordingly, if the band array operation matrix, ##EQU1## is diagonalized to find an eigenvalue, .gamma..sub.p and an eigenvector, U.sub.np, then there can be found from .gamma..sub.p and U.sub.np the Bloch functions in a one-to-one relation with two adjacent wave number vectors, k.sub.A and k.sub.

Abstract: A field effect transistor has a channel between a source electrode and a drain electrode made from an organic semiconductor. In one form of the invention, the channel is a mixture of at least two different organic compounds. In another form of the invention, the channel is a lamination of at least two films of different organic compounds. The channel can also be a .pi.-conjugated block copolymer of at least two different types of monomers.