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精确计算核磁共振屏蔽常数的扩展焦点分析方法 被引量:1
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作者 王康丽 孙萌 吴安安 《厦门大学学报(自然科学版)》 CAS CSCD 北大核心 2018年第2期157-163,共7页
在焦点分析(FPA-M)方法的基础上,提出了计算屏蔽常数的FPA-M-HF方法.通过外推HF(Hartree-Fock)屏蔽常数至完全基组(complete basis set,CBS)极限,并加上较小基组下CCSD(T)与HF计算屏蔽常数的差值作为高阶相关校正,得到近似CCSD(T)/CBS... 在焦点分析(FPA-M)方法的基础上,提出了计算屏蔽常数的FPA-M-HF方法.通过外推HF(Hartree-Fock)屏蔽常数至完全基组(complete basis set,CBS)极限,并加上较小基组下CCSD(T)与HF计算屏蔽常数的差值作为高阶相关校正,得到近似CCSD(T)/CBS屏蔽常数.研究表明:在cc-pCVnZ和pcJ-n两个基组下,FAP-M-HF可以精确计算13C,15N,17O和19F原子的屏蔽常数,并且超过了CCSD(T)/cc-pV5Z的精确度. 展开更多
关键词 屏蔽常数 核磁共振 焦点分析方法
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气相^(17)O核磁共振化学屏蔽常数与化学位移的理论研究 被引量:1
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作者 陈茹婷 吴安安 《厦门大学学报(自然科学版)》 CAS CSCD 北大核心 2022年第5期762-767,共6页
系统地研究了不同计算方法在气相^(17)O化学屏蔽常数与化学位移计算中的表现.结果表明:在19个含氧化合物的分子集中,适用于磁性质计算的焦点分析(FPA-M)方法在化学屏蔽常数和化学位移的计算中均有最佳表现,明显优于大基组下的包含三重... 系统地研究了不同计算方法在气相^(17)O化学屏蔽常数与化学位移计算中的表现.结果表明:在19个含氧化合物的分子集中,适用于磁性质计算的焦点分析(FPA-M)方法在化学屏蔽常数和化学位移的计算中均有最佳表现,明显优于大基组下的包含三重激发微扰校正的耦合簇(CCSD(T))方法;在本文研究的所有密度泛函中,xOPBE的表现最佳(尽管设计的特定目的是提供准确的^(13)C化学位移),在各个方面都显著优于常用的密度泛函.因此对于化学位移的常规计算,无论是^(13)C还是^(17)O,都推荐使用xOPBE密度泛函. 展开更多
关键词 ^(17)O核磁共振 焦点分析方法 密度泛函
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Faster Focus Group Interviews--CurroCus Groups--An Improved Faster Approach to Collect Consumer Data
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作者 Kai Victor Hansen Hilde Kraggerud 《Sociology Study》 2011年第7期484-490,共7页
There is a need for cost-efficient methods in consumer research. Existing qualitative methods are expensive to conduct. This paper aims to improve the focus group method. The objective was to improve focus groups with... There is a need for cost-efficient methods in consumer research. Existing qualitative methods are expensive to conduct. This paper aims to improve the focus group method. The objective was to improve focus groups with different aims: shorter time conducting interviews, interview greater number of respondents, deliver results faster than traditionally analysis of data, and lower total cost. CurroCus groups of 15-45 minutes duration were tested in five different experiments, including 70 to 160 respondents in groups of 7-11 respondents. The name of the new method is formed from the word "Curro" in Latin that means speed in English, and "Cus" that is the last syllable of the word "focus", thereby forming a new word: CurroCus~ on the method. The results from testing of the CurroCus~ group method at different cases showed that trained moderators and observers could collect relevant responses in a given time for each group. It was possible to process a number of 6 to 10 respondents for each group. By conducting several successive groups, saturation of information was reached after an adequate number of CurroCus~ groups. Therefore, the total number of respondents can be optimized and results can be more precise, with reduced risk of inaccuracy. At the same time, the cost for each case can be lowered substantially, in our cases to approximately 1/10 of a traditional focus group cost. The role (skills) of the moderator is important. A disadvantage is the risk that some of the respondents are not able to express their thoughts in due time when time is limited. There is a need for more research on all parts of the CurroCus group process. 展开更多
关键词 CONSUMER CurroCus group FOCUS method development speed
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