Dipole moments computational study

One interesting species, unknown until recently, is HOF, which was studied by Peslak et al.,611 and electron-density contour maps were described. More recently, it was studied by Kim and Sabin.512 The computed bond lengths with a near-minimal GTO basis were i (H—O) = 1.080 A, J (0—F) = 1.450 A, and 0 = 100.8°, in fair agreement with the results of a microwave investigation. Force constants were computed and the population analysis was reported. A more extensive basis set was used in a similar calculation by Ha, who computed a dipole moment of 2.72 D.513... 

CASSCF wave functions with their own sets of optimized orbitals, which where then not orthogonal to each other. The CAS State interaction CASSI, method made it possible to compute efficiently first and second order transition density matrices for any type of CASSCF wave functions [16, 17]. The method is used to compute transition dipole moments in spectroscopy and also in applications where it is advantageous to use localized orbitals, for example in studies of charge transfer reactions [18]. Today, the same approach is used to construct and solve a spin-orbit Hamiltonian in a basis of CASSCF wave functions [19]. 

Figure 2.7 shows the optical spectra generated from the SAC-CI calculations for each of the systems studied. The spectra were obtained non-perturbatively, by explicitly computing transition dipole moment and oscillator strength for... 

The computational results (93JA2465) are consistent with the experimental findings of NMR spectroscopic studies (82JOC5132 97MRC35), which showed the presence of only the H tautomer of tetrazole in DMSO-dfi e = 49) solution. The content of H tautomer 27a in dioxane e = 22) at 30°C was estimated as 78% (82JST283) and 85% (75BSF1675) from its dipole moment 4.88 D and those of 1,5- and 2,5-dimethyltetrazoles as models for the H and 2H tautomers respectively. 

In a combined experimental/computational study, the vibrational spectra of the N9H and N7H tautomers of the parent purine have been investigated [99SA(A) 2329]. Solvent effects were estimated by SCRF calculations. Vertical transitions, transition dipole moments, and permanent dipole moments of several low-lying valence states of 2-aminopurine 146 were computed using the CIS and CASSCF methods [98JPC(A)526, 00JPC(A)1930]. While the first excited state of adenine is characterized by an n n transition, it is the transition for 146. The... 

MD simulations in expHcit solvents are stiU beyond the scope of the current computational power for screening of a large number of molecules. However, mining powerful quantum chemical parameters to predict log P via this approach remains a challenging task. QikProp [42] is based on a study [3] which used Monte Carlo simulations to calculate 11 parameters, including solute-solvent energies, solute dipole moment, number of solute-solvent interactions at different cutoff values, number of H-bond donors and acceptors (HBDN and HBAQ and some of their variations. These parameters made it possible to estimate a number of free energies of solvation of chemicals in hexadecane, octanol, water as well as octanol-water distribution coefficients. The equation calculated for the octanol-water coefficient is ... 

A formally antiaromatic 1,4-dihydropyrazinothiadiazole has been prepared and characterized by single crystal X-ray spectroscopy. The antiaromatic character of which has been supported computationally using NICS measurements <20070L1073>. CHIH-DFT computational studies on acenaphtho[l,2-f]-l,2,5-thiadiazole 1,1-dioxide led to simulations of its infrared (IR) and ultraviolate (LJV) spectra, the dipole moment and polarizability <2007JMT373>. 4,6-Dinitrobenzothiadiazole was determined to have an electrophilic reactivity of —8.40 which corresponds to a pK z° of 7.86 for Meisenheimer complexation with water and is close to the demarcation boundary (E = —8.5) between super-and normal-electrophiles and between reactive dienophiles and inert partners in Diels-Alder adduct formation <20070BC1744>. 

As a demonstration of the power and versatility of the MM3(2000) force field, a comparative study of dipole moments was computed on forty-four small organic molecules. A segment of those results are discussed here with an emphasis on the improvement of the MM3(2000) force field due to the inclusion of the induced dipole moments. 

Another transport property of interfacial water which can be studied by MO techniques is the dipole relaxation time. This property is computed from the dipole moment correlation function, which measures the rate at which dipole moment autocorrelation is lost due to rotational motions in time (63). Larger values for the dipole relaxation time indicate slower rotational motions of the dipole... 

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