CAJ | 학술논문

采用完全活性空间自洽场方法(CASSCF)以及组合的量子化学ONIOM方法,研究了硝基甲烷受限于椅式(5,5)单壁碳纳米管内的结构及热解过程.分子结构分析表明,椅式(5,5)碳纳米管内的硝基甲烷其构型发生扭转,Cs对称性消失,C-N键长略微缩短.热解势能面分析发现,硝基甲烷单体沿C-N键的热解是一个无过渡态的解离过程,而硝基甲烷在椅式(5,5)碳纳米管内的热解需经历一个过渡态,所需克服的能垒约为198 kJ·mol~(-1),比硝基甲烷单体的解离能降低了21 kJ·mol~(-1)左右.此外,计算结果还表明,椅式(5,5)碳纳米管内的硝基甲烷热解过程中的分子结构、NO_2和CH_3基团电荷变化与单体解离过程亦有所不同.
채용완전활성공간자흡장방법(CASSCF)이급조합적양자화학ONIOM방법,연구료초기갑완수한우의식(5,5)단벽탄납미관내적결구급열해과정.분자결구분석표명,의식(5,5)탄납미관내적초기갑완기구형발생뉴전,Cs대칭성소실,C-N건장략미축단.열해세능면분석발현,초기갑완단체연C-N건적열해시일개무과도태적해리과정,이초기갑완재의식(5,5)탄납미관내적열해수경력일개과도태,소수극복적능루약위198 kJ·mol~(-1),비초기갑완단체적해리능강저료21 kJ·mol~(-1)좌우.차외,계산결과환표명,의식(5,5)탄납미관내적초기갑완열해과정중적분자결구、NO_2화CH_3기단전하변화여단체해리과정역유소불동.
The molecular structures and thermal decomposition of nitromethane confined inside a armchair (5,5) single-wall carbon nanotube were studied by using the complete active space self-consistent field (CASSCF) and ONIOM level of theory. Results show that nitromethane confined inside a CNT (5,5) has no Cs symmetry and the C-N bond becomes short slightly. Analysis of the potential energy curves along the C-N bond length shows that a transition state exists for the thermal decomposition of nitromethane/ CNT(5 ,5 ) , which is different from that of nitromethane monomer (no transition state for the C-N bond dissociation). For nitromethane/CNT (5,5) ,the energy barrier of the transition state is calculated to be about 198 kJ · mol~(-1), which is about 21 kJ · mol~(-1) lower than that of the C-N bond dissociation energy of nitromethane monomer. In addition, calculated results show that the (5,5) single-wall carbon nanotube has effect on the changing in the molecular structure and electronic charge of NO_2 and CH_3 groups during the thermal decomposition process of nitromethane.