[[alternative]]The Theoretical Investigation in Nano-Electronic Materials

計畫編號：NSC93-2113-M032-008研究期間：200408~200507研究經費：1,102,000[[abstract]]我們主要的研究方向有：(A)有機發光二極體(OLED)其中之maleimide 衍生物其 相關之光學性質。(B) 有機發光材枓之電荷傳導率之理論探討。(C)薄膜技術之蒙地 卡羅方法之分子模擬。 (A) 有機發光二極體(OLED) 自從1987 年Alq3 被合成後，OLED 的研究被廣泛的重視。Red、Green 及Blue 三原色之OLED 分子合成及其應用已為有機化學家提出甚多。這些OLED 分子都有 其電子非定域化的共同性。在致光的機制上都是* 之電子轉移。在本計劃 中我們將以MLH 及DCM 為探討對像以理論計算配合ZINDO、TD-DFT 及HF(CIS) 等方法求得其光譜性質包括(absorption 及emission)及λmax 並與實驗數據相互配合。 而MLH 及DCM 發光分子如有很強的Stokes shift 而產生Stokes shift 之產生機制以 及基態與激發態之幾何結構比較也將於此計劃中進行。另者尋求一個相對準確之化 學計算方法也是目前材料學界所迫切需要的。我們也將在本計劃中尋找好的計算方 法，並得到各項方法於發光材料光譜性質中之準確度已為未來實驗之參考。 (B) 有機發光材枓之電荷傳導率之理論探討 根據簡化的Marcus Theory 得知重組能(reorganization energy λ) 與電荷傳導率有 關。從這個方向我們可以由DFT 與AM1 等方法來計算分子在不同狀態時的能量來 求得重組能，並且由此來預測分子的電荷傳導率大小。 而有機分子在應用上重要的一項性質就是關於電荷遷移率(charge mobility)，可 以細分為電洞傳導(hole transport)和電子傳導(electron transport)兩種性質，這兩種性 質可視為反向的傳導。從我們所計算得的分子結構和傳導性質之間的關係是我們主 要可以提供元件設計的重點，從這裡我們可以去發掘更優秀或是改進電荷遷移率的 性質。 (C) 薄膜技術之蒙地卡羅方法之分子模擬 利用蒙地卡羅(Monte Carlo)模型研究了薄膜生長的初始階段島的形貌和島的尺 寸與基底溫度之間的關係。模型中我們將會考慮原子沉積(adsorption)、吸附原子擴 散(diffusion)和蒸發過程(reevaporation)。並詳加探討隨基底溫度的升高，島的形貌歷 經一個從分形生長到凝聚生長的變化過程，而且希望能夠進一步瞭解島的生長和基 底溫度之間的關係。[[sponsorship]]行政院國家科學委員

[[alternative]]Theoretical Investigation of Nanomaterials (II)

計畫編號：NSC92-2113-M032-010研究期間：200308~200407研究經費：1,200,000[[sponsorship]]行政院國家科學委員

A semiempirical study of carbon nanotubes with finite tubilar length and various tubular diameters

[[abstract]]A semiempirical PM3 quantum computational method has been used to generate the electronic and optimized geometrical structure of SWNT of zigzag and armchair types. We shed light on the electronic structures of SWNT with various diameters and lengths of the tube. Particularly, the calculated HOMO, LUMO and band-gap of SWNT are not monotonic but exhibit a well-defined oscillation, which depends on the tubular diameter and the tubular length. Calculated HOMO, LUMO and band-gap of the zigzag SWNTs have oscillated with tubular diameter as they contain an odd or even number of benzenoids in the circular plane of the carbon nanotube. The zigzag SWNTs with an odd number of benzenoids have a higher band-gap than those of SWNTs with an even number of benzenoids in the circular plane of the carbon nanotube. Calculated results also reveal that the tubular length in the zigzag SWNTs influences the band-gaps very little. For the armchair SWNT, calculated HOMO, LUMO and band-gap contained the oscillate depending on the number of carbon sections in the tubular length axis. Their repeat sections are 3n-1, 3n and 3n+1. The armchair SWNT with 3n+1 sections has a high band-gap while the SWNTs with 3n-1 sections have a low band-gap. The tubular diameters of armchair SWNT influence the HOMO, LUMO and band gap very little.[[incitationindex]]SCI[[booktype]]紙

[[alternative]]Theoretical studies on electronic properties of pyrene and its derivatives

[[abstract]]藉由ab initio (HF、DFT and MP2)及semiempirical method (AM1、PM3 and ZINDO)對芘(pyrene)中心發色團的分子結構、HOMO、LUMO、分子軌域能階及UV電子光譜(electronic spectrum)進行詳細之研究，得到AM1搭配ZINDO的理論計算結果與實驗數據相當近似。進而以AM1和ZINDO方法對芘的1、2和4單取代衍生物進行取代基及取代位置探討時，若取代基為拉電子則LUMO呈現下降趨勢，推電子時則HOMO呈現上升趨勢，惟兩者皆具有降低HOMO-LUMO能隙之功能；對電子光譜方面而言，取代基在1和4位置時，其π→π*呈現較大的紅位移，而芘發色團上同時加入推、拉電子基時，則其π→π*電子光譜將產生更大的紅位移。惟取代基過大將造成平面結構扭曲而減小軌域重疊度，致使電子不易由基態(ground state)躍遷至激發態(excited state)，而產生少許藍位移。綜上所得，本研究再以AM1和ZINDO方法對文獻上數個藍光的芘衍生物進行計算比對，得到理論計算結果與其實驗值相當吻合，預期本理論計算研究程序將可成功探討分子材料之電子性質，並將之應用到目前相當熱門的OLED材料上。[[notice]]補正完畢[[journaltype]]國

[[alternative]]重排反應之理論探討在C60, C76及C84球烯

[[abstract]]We present the results of a semiempirical study of C60 (Ih, D6h, C3v, C3, D5), C76 (Td, D2, C3) and C84, (Td, C3, C3v) fullerenes and their isomer skeletal rearrangements. We have proposed four different intramolecular rearrangements in the fullerenes. The interconversion between two isomeric fullerene are carried out by these intramolecular rearrangements. The 2-D Schlegel diagrams with symmetry analysis for fullerenes are used to find the possible reaction mechanism in the geometry interconversion. We use semiempirical methods MNDO and MM2 (which are implemented in Spartan 3.1 program) to compute the heats of formation, steric strain energy, electronic structure and Δɛ (HOMO-LUMO) for these carbon cages. Estimates are presented for activation energy and enthalpy change of isomerization. The transition states in the reaction are also generated. The results suggest that C60Ih), C76(D2) and C84 (D6h) are the global minimum structure of C60 (7 isomers), C76, (3 isomers), and C84 (3 isomers) respectively.[[notice]]補正完畢[[journaltype]]國

巨球烯之幾何結構

[[notice]]本書目待補

Effect of substituent and solvent on the structure and spectral properties of maleimide derivatives

[[abstract]]The maximum absorption wavelength View the MathML source, emission wavelength (λem) and the related oscillator strength (f) of the maleimides in the ground and first excited states were calculated by using the DFT, CIS and the time-dependent density functional theory (TD-DFT) methods, where the molecular structures were optimized by DFT/B3LYP/6-31G∗ calculation. Solvent effects on the maleimides were examined using the PCM simulation at DFT/B3LYP level with the 6-31G∗ basis set. For N -substituted maleimide, the substituent gives only a slight influence on the maleimide chromophore, while planar conformation of PhMLH leads to the improvement in π-delocalization from substituent to maleimide unit. For 3,4-substituted maleimide, the steric repulsion between substituent and maleimide chromophore influences the extent of π-delocalization and the molecular conformation. The calculated View the MathML source and λem of maleimides are in good agreement with the experimental data. In the gas phase, both absorption and emission peaks are red-shift as compared to the non-substituted maleimide. Under solvent environment, the more planar conformation of PhMLH shows a blue-shift in the calculated View the MathML source and λem as compared with other N-substituted maleimides. For 3,4-substituted maleimides, the effect of substitution produces the most significant spectral red-shift as compared to other maleimides.[[notice]]補正完畢[[incitationindex]]SC

A PBC-DFT study of infinite single-walled carbon nanotubes with various tubular diameters

[[notice]]本書目待補正[[conferencedate]]20060822~2008091

Structures and stabilities of C60(OH)6 and C60(OH)12 fullerenols

[[abstract]]Recently, Chiang's group have prepared water-soluble polyhydroxylated C60 derivatives (Fullerenols) in fuming sulfuric acid via hydrolysis of polycyclosulfated precursors. A suggested reaction mechanism is proposed. The calculation of different isomers of C60(OH)6 and C60(OH)12 fullerenols has been carried out using the semiempirical MNDO and MM2 methods with two different approaches: 1.(a) consideration of the geometries and thermodynamic stabilities; 2.(b) consideration of the cyclosulfation and hydrolysis reaction mechanisms. For (a), the double bonds in the pentagon lead to a decrease in the electron delocalization energy. Thus, the ΔHfO values of fullerenol are predicted to increase for each double bond placed in the pentagon for these fullerenols. According to the ΔHfo values, the most stable structures of C60(OH)6 and C60(OH)12 with externally bound hydroxyl groups have been generated, with Cs and S6 symmetries respectively. The ΔHfOvalues for these fullerenols are 503 kcal mol−1 (C60(OH)6) and 131.8 kcal mol−1 (C60(OH)12). According to the geometric structure of C60(OH)6 and C60(OH)12 fullerenol, multi-hydroxy additions follow 1,2- or 1,4- addition to a cyclohexatriene. For (b) the most likely products in this reaction are C60(OH)6 (Cs) and C60(OH)12 (S6), whose ΔHfOvalues are 573 and 141.5 kcal mol−1, respectively. These stable structures could contain exact hydroxyl group sites in C60, and they may be helpful in the investigation of the physical properties of polymers or other groups substituted onto fullerenols (called star-like polymers).[[notice]]補正完

A Semiempirical study of Nanotube with finite tubular length and tubular diameter

本書目待補正20031128~1997010