相关实验视频
Updated: Jul 10, 2026

09:50
Preparation and Reactivity of Gasless Nanostructured Energetic Materials
Published on: April 2, 2015
结构,崎的能量景观,以及Al (n) (2<或=n<或=65) 颗粒的纳米热力学
Zhen Hua Li1, Ahren W Jasper, Donald G Truhlar
1Department of Chemistry and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431, USA.
Journal of the American Chemical Society
|November 13, 2007
概括
温度显著影响金属纳米粒子的结构和稳定性. 即使是低温也会使理论上稳定的结构变得不稳定,影响它们的特性和新兴技术中的反应性.
科学领域:
- 计算材料科学 计算材料科学
- 物理化学 物理化学
- 纳米技术纳米技术
背景情况:
- 金属纳米粒子对于新兴技术至关重要.
- 对尺寸选择的热力学性质的实验性确定具有挑战性.
- 了解纳米粒子结构-属性关系需要先进的计算方法.
研究的目的:
- 描述 (Aln) 纳米颗粒的能量和结构性质.
- 研究温度对纳米粒子稳定性和主导结构的影响.
- 为多同位素纳米颗粒的热化学特性提供见解.
主要方法:
- 使用验证的多体分析潜力进行分子动力学火模拟.
- 计算全球最低能量结构和当地最低能量分布.
- 对有限温度热力学的振动分区函数的评估.
主要成果:
- 主导的纳米粒子结构依赖于尺寸和温度.
- 电子魔术数字在高温下可能变得不稳定 (例如,n=38 Aln在>= 500 K).
- 能源景观分析显示,在温和的温度下,全球最小结构往往不占主导地位.
结论:
- 统计力学和电子结构都对确定纳米粒子属性至关重要.
- 有限温度效应显著改变纳米粒子稳定性和异构体的主导地位.
- 异构体能量 (EIso) 是一个有用的指标,用于表示多异构体系统的热化学特性.
相关概念视频
Metallic Solids
Metallic solids such as crystals of copper, aluminum, and iron are formed by metal atoms. The structure of metallic crystals is often described as a uniform distribution of atomic nuclei within a “sea” of delocalized electrons. The atoms within such a metallic solid are held together by a unique force known as metallic bonding that gives rise to many useful and varied bulk properties.
All metallic solids exhibit high thermal and electrical conductivity, metallic luster, and malleability. Many...
All metallic solids exhibit high thermal and electrical conductivity, metallic luster, and malleability. Many...
Structure and Bonding of Alkenes
Olefins, which are unsaturated hydrocarbons containing one or more carbon–carbon double bonds, are broadly divided into alkenes and cycloalkenes. The general chemical formula of an alkene is CnH2n.
Doubly bonded carbons are sp2 hybridized and have a trigonal planar geometry. The double bond is composed of a σ bond formed by the overlap of hybrid orbitals and a π bond produced by the lateral overlap of unhybridized 2p orbitals on both the carbons. Each carbon atom is bonded to two hydrogen atoms...
Doubly bonded carbons are sp2 hybridized and have a trigonal planar geometry. The double bond is composed of a σ bond formed by the overlap of hybrid orbitals and a π bond produced by the lateral overlap of unhybridized 2p orbitals on both the carbons. Each carbon atom is bonded to two hydrogen atoms...
Relative Stabilities of Alkenes
The relative stability of alkenes can be determined by comparing their heats of hydrogenation. The lower heat of hydrogenation indicates the more stable alkene. The three main factors determining the relative stability of alkenes are i) the number of substituents attached to the double-bond carbon atoms, ii) hyperconjugation, and iii) the stereochemistry of the double bond.
Nitriles to Amines: LiAlH4 Reduction
Nitriles are reduced to amines in the presence of strong reducing agents like lithium aluminum hydride through a typical nucleophilic acyl substitution. The reaction requires two equivalents of the reducing agent. The reducing agent acts as a source of hydride ions.
As shown below, the mechanism involves three steps. Firstly, the hydride ion acting as a nucleophile attacks the nitrile carbon to form an anion. In the second step, a second equivalent of the hydride ion attacks the anion to...
As shown below, the mechanism involves three steps. Firstly, the hydride ion acting as a nucleophile attacks the nitrile carbon to form an anion. In the second step, a second equivalent of the hydride ion attacks the anion to...
Structure of Alkanes
The formation of carbon-carbon bonds leading to the creation of the carbon chain is the basis of organic chemistry. August Kekulé and Archibald Scott Couper independently developed this idea of carbon chain formation.
Hydrocarbons are the simplest organic compounds composed of carbons and hydrogens. Based on the bond order between carbons, the hydrocarbons are further classified into alkanes, alkenes, and alkynes.
Alkanes are the simplest hydrocarbons with sp3 hybrid carbon atoms. These sp3...
Hydrocarbons are the simplest organic compounds composed of carbons and hydrogens. Based on the bond order between carbons, the hydrocarbons are further classified into alkanes, alkenes, and alkynes.
Alkanes are the simplest hydrocarbons with sp3 hybrid carbon atoms. These sp3...
Structure and Physical Properties of Alkynes
Introduction:
In nature, compounds containing both carbon and hydrogen are known as "hydrocarbons". Aliphatic hydrocarbons are compounds whose molecules contain saturated single bonds (i.e., alkanes) or unsaturated double or triple bonds. Alkenes contain carbon–carbon double bonds and have a structural formula CnH2n. Unsaturated hydrocarbons containing carbon–carbon triple bonds are called "alkynes" and are structurally represented by the formula CnH2n-2.
The simplest alkyne is ethyne, or...
In nature, compounds containing both carbon and hydrogen are known as "hydrocarbons". Aliphatic hydrocarbons are compounds whose molecules contain saturated single bonds (i.e., alkanes) or unsaturated double or triple bonds. Alkenes contain carbon–carbon double bonds and have a structural formula CnH2n. Unsaturated hydrocarbons containing carbon–carbon triple bonds are called "alkynes" and are structurally represented by the formula CnH2n-2.
The simplest alkyne is ethyne, or...

