SPOCK.CI: a multireference spin-orbit configuration interaction method for large molecules

We present SPOCK.CI, a selecting direct multireference spin-orbit configuration interaction (MRSOCI) program based on configuration state functions. It constitutes an extension of the spin-free density functional theory/multireference configuration interaction (DFT/MRCI) code by Grimme and Waletzke [J. Chem. Phys. 111, 5645 (1999)] and includes spin-orbit interaction on the same footing with electron correlation. Key features of SPOCK.CI are a fast determination of coupling coefficients between configuration state functions, the use of a nonempirical effective one-electron spin-orbit atomic mean-field Hamiltonian, the application of a resolution-of-the-identity approximation to computationally expensive spin-free four-index integrals, and the use of an efficient multiroot Davidson diagonalization scheme for the complex Hamiltonian matrix. SPOCK.CI can be run either in ab initio mode or as semiempirical procedure combined with density functional theory (DFT/MRSOCI). The application of these techniques and approximations makes it possible to compute spin-dependent properties of large molecules in ground and electronically excited states efficiently and with high confidence. Second-order properties such as phosphorescence rates are known to converge very slowly when evaluated perturbationally by sum-over-state approaches. We have investigated the performance of SPOCK.CI on these properties in three case studies on 4H-pyran-4-thione, dithiosuccinimide, and free-base porphin. In particular, we have studied the dependence of the computed phosphorescence lifetimes on various technical parameters of the MRSOCI wave function such as the size of the configuration space, selection of single excitations, diagonalization thresholds, etc. The results are compared to the outcome of extensive quasidegenerate perturbation theory (QDPT) calculations as well as experiment. In all three cases, the MRSOCI approach is found to be superior to the QDPT expansion and yields results in very good agreement with experimental findings. For molecules up to the size of free-base porphin, MRSOCI calculations can easily be run on a single-processor personal computer. Total CPU times for the evaluation of the electronic excitation spectrum and the phosphorescence lifetime of this molecule are below 40 h.     

Electronically excited states of tryptamine and its microhydrated complex

The lowest electronically excited singlet states of tryptamine and the tryptamine (H2O)1 cluster have been studied, using time dependent density functional theory for determination of the geometries and multireference configuration interaction for the vertical and adiabatic excitation energies, the permanent dipole moments, and the transition dipole moment orientations. All molecular properties of the seven experimentally observed conformers of tryptamine could be reproduced with high accuracy. A strong solvent reorientation has been found upon electronic excitation of the 1:1 water cluster of tryptamine to the L(a) and L(b) states. The adiabatically lowest excited singlet state in case of the tryptamine monomer is the L(b) state, while for the 1:1 water complex, the L(a) is calculated below the L(b) state.     

Synthesis and characterizations of new isotactic homopolyesters,statistical and block copolyesters derived of poly((S)‐3,3‐dimethylmalic acid) via the lactone route

This article presents the synthesis of a new family of synthetic isotactic polyesters derived from poly((S)‐3,3‐dimethylmalic acid) (PDMMLA). These polyesters are prepared via the lactone route bearing functionalized groups in its main or side chain. The aim of this work is twofold: metabolism and stereochemistry. First, the synthesis of these new polyesters is chosen to provide biodegradable polyesters biocompatible and bioassimilable by the human body. Next, the molecular chain of this family contains a stereogenic center in the aim to provide 100% isotactic homopolymers and copolymers (statistical and block). Finally, these polymers have been characterized by several analytical techniques: FTIR, ¹H and ¹³C NMR, SEC, DSC, and TGA. The greatest importance will be given to the ¹³C NMR and DSC to principally confirm the stereoregularity and crystallinity of these stereopolyesters. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1495–1507