New Gradient Correction Scheme for Electronically Nonadiabatic Dynamics Involving Multiple Spin States.

It has been recommended that the best representation to use for trajectory surface hopping (TSH) calculations is the fully adiabatic basis in which the Hamiltonian is diagonal. Simulations of intersystem crossing processes with conventional TSH methods require an explicit computation of nonadiabatic coupling vectors (NACs) in the molecular-Coulomb-Hamiltonian (MCH) basis, also called the spin-orbit-free basis, in order to compute the gradient in the fully adiabatic basis (also called the diagonal representation). This explicit requirement destroys some of the advantages of the overlap-based algorithms and curvature-driven algorithms that can be used for the most efficient TSH calculations. Therefore, although these algorithms allow one to perform NAC-free simulations for internal conversion processes, one still requires NACs for intersystem crossing. Here, we show that how the NAC requirement is circumvented by a new computation scheme called the time-derivative-matrix scheme.

Nonadiabatic Dynamics of 1,3-Cyclohexadiene by Curvature-Driven Coherent Switching with Decay of Mixing.

The photoinduced ring-opening reaction of 1,3-cyclohexadiene to produce 1,3,5-hexatriene is a classic electrocyclic reaction and is also a prototype for many reactions of biological and synthetic importance. Here, we simulate the ultrafast nonadiabatic dynamics of the reaction in the manifold of the three lowest valence electronic states by using extended multistate complete-active-space second-order perturbation theory (XMS-CASPT2) combined with the curvature-driven coherent switching with decay of mixing (κCSDM) dynamical method. We obtain an excited-state lifetime of 79 fs, and a product quantum yield of 40% from the 500 trajectories initiated in the S1 excited state. The obtained lifetime and quantum yield values are very close to previously reported experimental and computed values, showing the capability of performing a reasonable nonadiabatic ring-opening dynamics with the κCSDM method that does not require nonadiabatic coupling vectors, time derivatives, or diabatization. In addition, we study the ring-opening reaction by initiating the trajectories in the dark state S2. We also optimize the S0/S1 and S1/S2 minimum-energy conical intersections (MECIs) by XMS-CASPT2; for S1/S2, we optimized both an inner and an outer local-minimum-energy conical intersections (LMECIs). We provide the potential energy profile along the ring-opening coordinate by joining selected critical points via linear synchronous transit paths. We find the inner S1/S2 LMECI to be more crucial than the outer one.

Recommendation of Orbitals for G0W0 Calculations on Molecules and Crystals.

The many-body GW approximation, especially the G0W0 method, has been widely used for condensed matter and molecules to calculate quasiparticle energies for ionization, electron attachment, and band gaps. Because G0W0 calculations are well-known to have a strong dependence on the orbitals, the goal of the present work is to provide guidance on the choice of density functional used to generate orbitals and to recommend a choice that gives the most broadly accurate results. We have systematically investigated the dependence of G0W0 calculations on the orbitals for 100 molecules and 8 crystals by considering orbitals obtained with a diverse set of Kohn-Sham (KS) and generalized KS (GKS) functionals (63 functionals plus Hartree-Fock). The percentage of Hartree-Fock exchange employed in density functionals has been found to have strong influence on the predicted molecular ionization energy and crystal fundamental band gaps (with optimum values between 40 and 56%), but to have less effect on predicting molecular electron affinities. The low cost of the Gaussian implementation, even with hybrid functionals in periodic calculations, the better performance of global hybrids as compared to range-separated hybrids of either than screened exchange or long-range-corrected type, and the relatively low cost of global-hybrid-functional periodic calculations using Gaussians means that one can employ global-hybrid functionals at a very reasonable cost and obtain more accurate band gaps of semiconductors than are obtained by the methods currently widely employed, namely local gradient approximations. We single out three global-hybrid functionals that give especially good results for both molecules (100 in the test set) and crystals (8 in the test set, for all of which our benchmark data are the proper band gap rather than an optical band gap uncorrected for exciton effects).

Nonadiabatic Dynamics Algorithms with Only Potential Energies and Gradients: Curvature-Driven Coherent Switching with Decay of Mixing and Curvature-Driven Trajectory Surface Hopping.

Direct dynamics by mixed quantum-classical nonadiabatic methods is an important tool for understanding processes involving multiple electronic states. Very often, the computational bottleneck of such direct simulation comes from electronic structure theory. For example, at every time step of a trajectory, nonadiabatic dynamics requires potential energy surfaces, their gradients, and the matrix elements coupling the surfaces. The need for the couplings can be alleviated by employing the time derivatives of the wave functions, which can be evaluated from overlaps of electronic wave functions at successive time steps. However, evaluation of overlap integrals is still expensive for large systems. In addition, for electronic structure methods for which the wave functions or the coupling matrix elements are not available, nonadiabatic dynamics algorithms become inapplicable. In this work, building on recent work by Baeck and An, we propose new nonadiabatic dynamics algorithms that only require adiabatic potential energies and their gradients. The new methods are named curvature-driven coherent switching with decay of mixing (κCSDM) and curvature-driven trajectory surface hopping (κTSH). We show how powerful these new methods are in terms of computation time and accuracy as compared to previous mixed quantum-classical nonadiabatic dynamics algorithms. The lowering of the computational cost will allow longer nonadiabatic trajectories and greater ensemble averaging to be affordable, and the ability to calculate the dynamics without electronic structure coupling matrix elements extends the dynamics capability to new classes of electronic structure methods.

Sustained increased CaMKII phosphorylation is involved in the impaired regression of isoproterenol-induced cardiac hypertrophy in rats.

To understand the mechanism underlying the regression of cardiac hypertrophy, we investigated the pathological changes after isoproterenol (ISO) withdrawal in ISO-induced cardiomyopathy models in rats and neonatal cardiomyocytes. Cardiac hypertrophy was induced in rats by two weeks of ISO administration; however, the hypertrophy did not regress after three weeks of natural maintenance after ISO administration was withdrawn (ISO-wdr group). The remaining hypertrophy in the ISO-wdr group was accompanied by a sustained increase in the level of phosphorylated Ca2+/calmodulin-dependent protein kinase II (p-CaMKII). Additionally, the increased expression levels of histone deacetylase 4 (HDAC4) and the CaV1.2 channel and amounts of CaMKII bound with HDAC4 and CaV1.2 were not recovered in the ISO-wdr group. The results in cardiomyocyte models were similar to those seen in rat models. Losartan, metoprolol or amlodipine neither ameliorated the increase in atrial natriuretic peptide nor inhibited the increase in p-CaMKII and bound CaMKII. In contrast, autocamtide-2-related inhibitor peptide, a CaMKII inhibitor, reduced these increases. This study investigated the phosphorylation status of CaMKII after hypertrophic stimulus was withdrawn for the first time and proposed that CaMKII as well as its complexes with CaV1.2 could be potential targets to achieve effective regression of cardiac hypertrophy.

Distinct roles of calmodulin and Ca2+/calmodulin-dependent protein kinase II in isopreterenol-induced cardiac hypertrophy.

Intracellular calcium is related to cardiac hypertrophy. The CaV1.2 channel and Ca2+/calmodulin-dependent protein kinase II (CaMKII) and CaM regulate the intracellular calcium content. However, the differences in CaMKII and CaM in cardiac hypertrophy are still conflicting and are worthy of studying as drug targets. Therefore, in this study, we aim to investigate the roles and mechanism of CaM and CaMKII on CaV1.2 in pathological myocardial hypertrophy. The results showed that ISO stimulation caused SD rat heart and cardiomyocyte hypertrophy. In vivo, the HW/BW, LVW/BW, cross-sectional area, fibrosis ratio and ANP expression were all increased. There were no differences in CaV1.2 channel expression in the in vivo model or the in vitro model, but the ISO stimulation induced channel activity, and the [Ca2+]i increased. The protein expression levels of CaMKII and p-CaMKII were all increased in the ISO group, but the CaM expression level decreased. AIP inhibited ANP, CaMKII and p-CaMKII expression, and ISO-induced [Ca2+]i increased. AIP also reduced HDAC4, p-HDAC and MEF2C expression. However, CMZ did not play a cardiac hypertrophy reversal role in vitro. In conclusion, we considered that compared with CaM, CaMKII may be a much more important drug target in cardiac hypertrophy reversal.

Gasification reactivity of co-pyrolysis char from coal blended with corn stalks.

The gasification reactivity of coal and corn stalks co-pyrolyzed char is studied using thermogravimetric analysis, and the influence of co-pyrolysis on co-gasification reactivity is quantitatively characterized by synergy index. The results demonstrate that with increasing the pyrolysis temperature, the gasification reactivity of coal char gradually decreases, however, the gasification reactivity of CS char does not change monotonically. Furthermore, inhibition effect on co-gasification reactivity of 75% CS co-pyrolyzed char and se-pyrolyzed mixed char is shown at early stage of co-gasification and it gradually becomes synergistic effect as the co-gasification process progresses. However, the effect of the interaction of coal and CS in co-pyrolysis process on co-gasification reactivity is more important than that of the interaction of coal char and CS char in the co-gasification process. Finally, the optimal co-pyrolysis condition for obtaining highly reactivity char is that the ratio of CS in blend exceeds 70% at the pyrolysis temperature about 600 °C.