Solvent effects in electronically excited states using the continuum solvation model COSMO in combination with multireference configuration interaction with singles and doubles (MR-CISD)

An implementation of the COSMO continuum solvation model into the MCSCF and MR-CISD programs of the COLUMBUS program system is reported. Equilibrium solvation and non-equilibrium solvation models for the treatment of electronic excitations have been used. Solvatochromic effects have been computed for a representative set of n-* and -* states of formaldehyde, acrolein and pyrazine using several solvents ranging from some with apolar character to water. Agreement with experimental shifts is good within the limits of a continuum model.Contribution to the Jacopo Tomasi Honorary Issue     

C_(60)环酮衍生物C_(66)H_8O与C_(67)H_(10)O顺反异构体的结构及光谱研究

用AM1，INDO/CI方法研究了C60与2-环己烯-1-酮和2-环庚烯-1-酮[2+2]环加成所得衍生物C_(66)H8O和C67H1O的结构。结果表明，两种衍生物的顺反异构体都只具有C1对称，C66H8O的顺式异构具有较低的能量和较小的偶极矩，C67H10的顺式并构体能量较低，但偶极矩较大，以优化构型为基础，计算加成产物的UV谱，对电子跃迁进行了理论指认，并分析了光谱移动的原因。     

Theoretical studies of atmospheric molecules: SCF and correlated energy levels for the NO2, NO 2 + and NO 2 − systems

SCF and MC-SCF/CI calculations were carried out on the low-lying electronic states of NO₂, NO ₂ ⁺ and NO ₂ ^– , using a double-zeta quality basis set of contracted Gaussian functions. The calculations were performed primarily at the equilibrium geometry (R _NO = 2.25 a_o, _ONO=134 °) of theX ² A ₁ state of NO₂. SCF calculations on NO ₂ ⁺ in a linear conformation were also performed. Results are presented and compared with experiment and other calculations.Research supported in part by Air Force Delivery Orders F33615-72-M-5015 and MIPR889474-00117 and Air Force Office of Scientific Research and in part by the United States Energy Research and Development Administration.     

Potential energy surface for the Pd-H2 system: Comparison with matrix isolation experiments

Summary We present here those aspects of the Pd-H₂ potential energy surface that are most directly related to the questions raised by matrix isolation experiments for the formation of Pd(¹-H₂) and Pd(²-H₂) complexes. 125 points of this potential energy surface were obtained at a CI level using the CIPSI Scheme and including the order of 10⁵ configurations. Relativistic effects are included and shown not to be crucial in understanding the main features of the surfaces. The theoretical results serve to explain many features of the low-temperature experiments on the Pd-H₂ reaction, especially those concerning the spectroscopic changes observed when different noble gas supports, Kr or Xe, are utilized.On Sabbatical leave from Instituto de Física, UNAM     

The ground state of MoCr(O2CH)4 at theab initio SCF and CI levels. A symmetry adapted RHF energy functional with an artificial double minimum

Ab initio restricted Hartree-Fock (RHF) calculations carried out on the ground state of MoCr(O₂CH)₄ lead to two distinct energy minima according to the initial guess made for the set of trial vectors. It is shown that these two symmetry-adapted wavefunctions can be correlated with a twofold degenerate broken-symmetry solution previously characterized for the related system of higher symmetry Cr₂(O₂CH)₄. Complete CI expansions have been carried out from either RHF polarized wavefunction using as a basis the set of eight frontier MO's with high metal character. These expansions yield poorly resymmetrized wavefunctions. A similar CI expansion has finally been carried out from a wavefunction resymmetrized at the SCF level and corresponding to a saddle point of the RHF energy hypersurface. The total energy associated with this latter expansion is the lowest obtained in the present work. The natural orbital analysis corresponds to ()^1.86()^3.58()^1.54()^0.46()^0.42 (^*)^0.14 and shows that this resymmetrized CI expansion is in many respects similar to the correlated wavefunctions obtained for the homobinuclear parent systems.     

Analytical applications of Raman spectroscopy

In this article interaction of transition metal complexes with DNA and its applications in electrochemical DNA biosensors as hybridization indicator or electroactive marker of DNA are reviewed. Special emphasis has been given to the efforts for the development of new transition metal complexes and their interaction to DNA. DNA and polymers covalently conjugated with transition metal complexes were also reviewed.     

Be~(2 )等二电子系列基态关联能计算方法的研究

在组态相互作用模型的基础上对Ｂｅ２＋等二电子系列基态电子关联能的计算方法进行了研究，利用变分原理，采用Ｂ样条处理径向基，用“混合Ｌ”法处理角向基，给出Ｈｅ，Ｈ－，Ｌｉ＋，Ｂｅ２＋，Ｂ３＋等５种原子（离子）系列的有关计算结果，并与其它理论方法计算的结果作了对比，显示出Ｂ样条方法优越的计算能力．     

Conversion of benzoic acid into phenol in an ITMS under CI‐MSn conditions. Recognition of ortho‐chlorobenzoyl derivatives

Isomeric chlorobenzoyl cations (m/z 139), under collision‐induced experiments, fragment identically. Chlorobenzoyl cations can be efficiently converted into cholorophenol radical cations by the reaction with methanol in the ion trap analyzer under CI‐MSn conditions. The substitution of the carbonyl group with a hydroxyl moiety is able to induce an ortho effect, which is absent in the startingortho‐chlorobenzoyl cation. This transformation could be useful to recognize ortho‐chlorinated benzoyl derivatives without the need of MS spectrum comparison of the whole set of isomers. The method reported in this study could be applicable to biologically active molecules that dissociate to form the chlorobenzoyl cations under CI or CI collision‐induced dissociation conditions, such as indomethacin, the degradation products from the insect growth regulator 1‐(2‐chlorobenzoyl)‐3‐(4‐chlorophenyl) urea, and lorazepam.     

一个一维CI相变模型的进一步研究

对一个一维CI相变模型进行进一步研究。外势周期D具有一个临界值Dc。D < c时的相图与D > c时的相图非常地不同。当D < c时,相图随D而变化,且在D的大部分区域显示出Farey树结构。当D > c时,相图不再变化,且不满足Farey树结构。通过有效势F(u)研究了相变过程。     

Unnatural parity states of helium with screened Coulomb potentials

Effect of screened Coulomb (Yukawa) potentials on the doubly excited meta‐stable bound states and the resonance states with unnatural parities of the helium atom have been investigated in the framework of stabilization method using CI‐type basis functions. A total of 54 resonances (6 each of ¹D^o and ³D^o states, 12 each of ¹F^e and ³F^e states, 9 each of ¹G^o and ³G^o states) below the He⁺(3P) thresholds have been estimated by calculating the density of resonance states using a stabilization method. The resonances belong to the different 3lnl′ (n ≥ 3) series. We have also calculated the doubly excited ^1,3F^e and ^1,3G^o meta‐stable bound states of He atom below the He⁺ (2P) thresholds. The resonance energies and widths along with the meta‐stable bound states energies are reported for various screening parameters. In free atom case, some of the F‐wave resonance states and most of the cases, F‐ and G‐wave resonance widths are reported for the first time. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008