Bis-periazulene (cyclohepta[def ]fluorene), which is an unknown pyrene isomer, was synthesized as kinetically protected forms. Its triaryl derivatives 1c−e exhibited the superimposed electronic structures of peripheral, polarized, and open-shell π-conjugated systems. In contrast to previous theoretical predictions, bis-periazulene derivatives were in the singlet ground state. Changing an aryl group controlled the energy gap between the lowest singlet−triplet states.
A kinetically-stabilized nitrogen-doped triangulene cation derivative has been synthesized and isolated as the stable diradical with a triplet ground state that exhibits near-infrared emission. As was the case for a triangulene derivative we previously synthesized, the triplet ground state with a large singlet-triplet energy gap was experimentally confirmed by magnetic measurements. In contrast to the triangulene derivative, the nitrogen-doped triangulene cation derivative is highly stable even in solution under air and exhibits nearinfrared absorption and emission because the alternancy symmetry of triangulene is broken by the nitrogen cation. Breaking the alternancy symmetry of triplet alternant hydrocarbon diradicals by a nitrogen cation would therefore be an effective strategy to create stable diradicals possessing magnetic properties similar to the parent hydrocarbons but with different electrochemical and photophysical properties.
Adiabatic state preparation (ASP) can generate the correlated wave function by simulating the time evolution of wave function under the time-dependent Hamiltonian that interpolates the Fock operator and the full electronic Hamiltonian. However, ASP is inherently unsuitable for studying strongly correlated systems, and furthermore practical computational conditions for ASP are unknown. In quest for the suitable computational conditions for practical applications of ASP, we performed numerical simulations of ASP in the potential energy curves of N2, BeH2, and in the C2v quasi-reaction pathway of the Be atom insertion to the H2 molecule, examining the effect of nonlinear scheduling functions and the ASP with broken-symmetry wave functions with the S2 operator as the penalty term, contributing to practical applications of quantum computing to quantum chemistry. Eventually, computational guidelines to generate the correlated wave functions having the square overlap with the complete-active space self-consistent field wave function close to unity are discussed.
Green beans and roasted beans of coffee with Rio flavor were analyzed by gas chromatographyolfactometry to clarify the causal substances of Rio flavor in Brazilian coffee. In addition to 2,4,6-trichloroanisole (TCA) and 2,4,6-trichlorophenol (TCP), which are known as the main causal substances of Rio flavor, a new iodine-like flavor-causing compound, 2,6-dichlorophenol (DCP), was detected. The detected amounts of 2,6-DCP and 2,4,6-TCA were less than 0.1 and 0.1 ppb in Rio flavor-free coffee beans, 0.8 and 1.2 ppb in weak Rio flavored beans, and 3.0 and 2.6 ppb in strong Rio flavored beans, respectively. Musty and chlorine flavors were sensed more strongly in model coffee containing both 2,4,6-TCA and 2,6-DCP than in the coffee containing them individually. In the present study, 2,6-DCP was identified as a new causal substance of Rio flavor, and it was found that the presence of 2,4,6-TCA intensifies Rio flavor, as a synergy effect.
A Bayesian phase difference estimation (BPDE) algorithm
allows
us to compute the energy gap of two electronic states of a given Hamiltonian
directly by utilizing the quantum superposition of their wave functions.
Here we report an extension of the BPDE algorithm to the direct calculation
of the energy difference of two molecular geometries. We apply the
BPDE algorithm for the calculation of numerical energy gradients based
on the two-point finite-difference method, enabling us to execute
geometry optimization of one-dimensional molecules at the full-CI
level on a quantum computer. Results of numerical quantum circuit
simulations of the geometry optimization of the H2 molecule
with the STO-3G and 6-31G basis sets, the LiH and BeH2 molecules
at the full-CI/STO-3G level, and the N2 molecule at the
CASCI(6e,6o)/6-311G* level are given.
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