三氢-苯并吲哚啉方酸染料晶体中电荷转移过程的理论研究

由于具有良好的光化学稳定性、在可见光区和近红外区的强吸光性等优点,方酸类染料是目前最具潜力的小分子有机太阳能电池给体材料之一.然而,其空穴迁移机制并不明确,较低的迁移率限制了器件光电转换效率的提升.结合第一性原理计算、Marcus电子转移理论、主方程模拟,系统研究了三氢-苯并吲哚啉方酸(USQ-BI)染料的电子结构、分子堆积模式以及电荷转移性质.结果表明,由于空穴迁移路径上交替出现两种不同的分子堆积模式,驱动力呈现正负交错的特征,克服正驱动力的过程为空穴迁移的决速步.据此,提出了降低驱动力绝对值以增大迁移率的理论策略.进一步研究发现,在一些位点上引入氰基可以显著提高空穴转移耦合强度,从而提高空穴迁移率.最后,对USQ-BI中电子转移过程的研究发现,由于较大的重组能导致较小的电子转移速率,该晶体不能作为好的电子传输材料.

降钙素原对ICU全身炎症反应综合征患者病因诊断及预后的价值

目的探讨分析ICU全身炎症反应综合征患者测定降钙素原后对其病因诊断及预后的价值。方法选择我院2015年1月~2016年12月收治的80例ICU全身炎症反应综合征患者(脓毒症),作为实验组,另外选取同时期来我院ICU就诊的80非脓毒症患者作为对照组,两组患者均进行外周静脉血血清降钙素原(PCT)、c-反应蛋白(CRP)测定,观察两组患者的PCT、CRP动态测定效果,针对死亡组与存活组患者的PCT、CRP动态测定效果进行对比分析,并且分析影响预后的危险因素。结果经测定分析,实验组ICU全身炎症反应综合征患者在第1天、第3天、第5天的PCT水平均高于对照组,两组差异有统计学意义(P<0.05),CRP水平差异无统计学意义;另外,所有入选患者中,有119例患者存活,41例患者死亡,死亡组患者在第1天、第3天、第5天的PCT水平均高于存活组,两组差异有统计学意义(P<0.05),CRP水平差异无统计学意义;针对PCT水平进行分析,当PCT水平大于5.3μg/L时是影响预后的独立危险因素。结论降钙素原对于诊断ICU全身炎症反应综合征具有非常好的意义,并且可通过分析其水平评估预后效果,对于患者的健康非常重要。

9 668株临床念珠菌感染的菌种分布及耐药性变化

目的:通过回顾性分析本院念珠菌感染的菌种分布及耐药性的变化特点,为临床诊断真菌感染和指导合理使用抗真菌药物提供实验依据。方法:对本院2011—2018年间疑似感染真菌的患者进行分离培养鉴定,并利用ATB-Fungus 3的药敏试剂盒对真菌进行5种常规抗真菌药物的药敏检测试验。结果:共检出9 668株真菌,白色假丝酵母菌、光滑球拟假丝酵母菌、热带假丝酵母菌、近平滑假丝酵母菌、克柔假丝酵母菌的检出率分别为64.88%(6 273/9 668)、20.51%(1 983/9 668)、7.29%(705/9 668)、3.66%(354/9 668)、1.03%(100/9 668);9 668株真菌对伊曲康唑的耐药率最高,其次为氟康唑、5-氟胞嘧啶、伏立康唑和两性霉素B,总耐药率分别为25.11%、19.25%、5.31%、5.02%和0.33%( P<0.01);8年间真菌感染率呈上升趋势,分别为6.67%、6.75%、12.39%、12.51%、13.77%、17.50%、14.50%和15.91%( P<0.05)。 结论:真菌感染率不断上升,临床应该加大真菌检查力度,加强对真菌感染与耐药性的监测,以指导合理使用抗真菌药物。

Theory and algorithms for the excited states of large molecules and molecular aggregates

This project aims to attack the frontiers of electronic structure calculations on the excited states of large molecules and molecular aggregates by developing novel theoretical and computational methods. The methodology development is especially based on the time-dependent density functional theory (TDDFT) and valence bond (VB) theory, and is expected to be computationally effective and accurate as well. Research works on the following related subjects will be performed: (1) The analytical energy-derivative approaches for electronically excited state within TDDFT will be developed to reduce bypass the computational costs in the calculation of molecular excited-state properties. (2) The ab initio methods for electronically excited state based on VB theory and hybrid TDDFT-VB method will be developed to overcome the limitations of current TDDFT in simulating photophysics and photochemistry. (3) For larger aggregates, neither ab initio methods nor TDDFT is applicable. We intend to build the effective model Hamiltonian by developing novel theoretical and computational methods to calculate the involved microscopic physical parameters from the first-principles methods. The constructed effective Hamiltonian is then used to describe the excitonic states and excitonic dynamics of the natural or artificial photosynthesized systems, organic or inorganic photovoltaic cell. (4) The condensed phase environment is taken into account by combining the developed theories and algorithms based on TDDFT and VB with the polarizable continuum solvent models (PCM), molecular mechanism (MM), classical electrodynamics (ED) or molecular dynamics (MD) theory. (5) Highly efficient software packages will be designed and developed.

Theoretical study of the low-lying electronic excited states for molecular aggregates

We present here a brief summary of a National Natural Science Foundation Major Project entitled "Theoretical study of the low-lying electronic excited state for molecular aggregates". The project focuses on theoretical investigation of the electronic structures and dynamic processes upon photo-and electric-excitation for molecules and aggregates. We aim to develop reliable methodology to predict the optoelectronic properties of molecular materials related to the electronic excitations and to apply in the experiments. We identify two essential scientific challenges: (i) nature of intramolecular and intermolecular electronic excited states; (ii) theoretical description of the dynamic processes of the coupled motion of electronic excitations and nucleus. We propose the following four subjects of research: (i) linear scaling time-dependent density-functional theory and its application to open shell system; (ii) computational method development of electronic excited state for molecular aggregates; (iii) theoretical investigation of the time evolution of the excited state dynamics; (iv) methods to predict the optoelectronic properties starting from electronic excited state investigation for organic materials and experimental verifications.

Theoretical studies of vibrationally resolved absorption and emission spectra: From a single chromophore to multichromophoric oligomers/aggregates

Absorption and photoluminescence spectroscopies are useful tools to study the photo-physical properties of materials. The theoretical methods for calculation of the spectra of molecules/supermolecules and aggregates, whose structures can differ significantly, are reviewed from the viewpoint of computational efficiency. Several model compounds/multimers are taken as examples for the spectral calculations. The numerical results achieve a satisfactory agreement between the theory and experiment.

Analytical derivative techniques for TDDFT excited-state properties:Theory and application

We review our recent work on the methodology development of the excited-state properties for the molecules in vacuum and liquid solution.The general algorithms of analytical energy derivatives for the specific properties such as the first and second geometrical derivatives and IR/Raman intensities are demonstrated in the framework of the time-dependent density functional theory(TDDFT).The performance of the analytical approaches on the calculation of excited-state energy Hessian has also been shown.It is found that the analytical approaches are superior to the finite-difference method on the computational accuracy and efficiency.The computational cost for a TDDFT excited-state Hessian calculation is only 2–3 times as that for the DFT ground-state Hessian calculation.With the low computational complexity of the developed analytical approaches,it becomes feasible to realize the large-scale numerical calculations on the excited-state vibrational frequencies,vibrational spectroscopies and the electronic-structure parameters which enter the spectrum calculations of electronic absorption and emission,and resonance Raman spectroscopies for medium-to large-sized systems.

Theoretical investigation of the non-Condon effect on electron transfer:Application to organic semiconductor

The non-Condon effect plays an important role in the process of electron transfer (ET). Several theoretical models have been proposed to investigate its effect on ET rates. In this paper,we overview a theoretical method for the calculations of the non-Condon ET rate constants proposed by us,and its applications to organic semiconductors. First,full quantum expressions of the non-Condon ET rates are presented with the electronic couplings having exponential,Gaussian and linear dependences in terms of the nuclear coordinates,respectively. The proposed formulas have closed forms in time domain and they thus can be easily applied in multi-mode systems. Then,the driving force dependences of the ET rates involving the non-Condon effect are calculated with the use of full quantum mechanical formulas. It is found that these dependences show very different prop-erties from the Marcus one. As an example of applications,the approaches are used to investigate the non-Condon effect on the mobility of the organic semiconductor dithiophene-tetrathiafulvalene (DT-TTF). The results manifest that the non-Condon ef-fect enhances ET rates compared with the Condon approximation,and static fluctuations of electronic coupling dominate the ET rate in the DT-TTF,which has been confirmed by the molecular dynamics simulation.