Opto-electronic properties of adamantane and hydrogen-terminated sila- and germa-adamantane: A comparative study

Marsusi, Farah; Mirabbaszadeh, Kavoos; Mansoori, G. Ali

doi:10.1016/j.physe.2008.12.021

Cited by 30 publications

(30 citation statements)

References 35 publications

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“…and cubic supercells of side length 32 to 60 a.u., depending on the size of the molecules, were used in our LDA calculations. According to previous work, 7 the Gaussian polarized double-diffuse 6-311++G * * basis set 20,21 is suitable for studying the energy levels of diamondoids and thus was used for all B3LYP and TD-B3LYP calculations in this study. Dirac-Fock (DF) average relativistic effective-core pseudopotentials were used to represent the ionic cores.…”

Section: Methodsmentioning

confidence: 99%

“…The effect of ZPE corrections on the adiabatic ionization potentials (IPs) of adamantane and sila-adamantane (Si 10 H 16 ) using the B3LYP functional has been calculated in Ref. 7. In contrast to sila-adamantane, the ZPE makes a significant contribution to the IP of adamantane.…”

Section: B Dmc Optical Gap Of Methane and Benchmarkingmentioning

confidence: 99%

“…A great deal of theoretical effort using different many-body techniques has been devoted to calculating the absorption gaps of diamondoids, which are often referred to as optical gaps (OGs). [3][4][5][6][7] However, the measured energy emitted from these materials and the corresponding emission gap (EG) is also of great technological importance. To our knowledge, no previous theoretical study has investigated the Stokes shift-the difference of the absorption and EGs-exhibited by these novel materials.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of quantum Monte Carlo with time-dependent and static density-functional theory calculations of diamondoid excitation energies and Stokes shifts

2011

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We compute the absorption and emission energies and hence Stokes shifts of small diamondoids as a function of size using different theoretical approaches, including density-functional theory (DFT) and quantum Monte Carlo (QMC) calculations. The absorption spectra of these molecules are also investigated by time-dependent DFT and compared with experiment. We analyze the structural distortion and formation of a self-trapped exciton in the excited state, and we study the effects of these on the Stokes shift as a function of size. Compared to recent experiments, QMC overestimates the excitation energies by about 0.8(1) eV on average. Benefiting from a cancellation of errors, the optical gaps obtained in DFT calculations with the B3LYP functional are in better agreement with experiment. It is also shown that time-dependent B3LYP calculations can reproduce most of the features found in the experimental spectra. According to our calculations, the structures of diamondoids in the excited state show a distortion which is hardly noticeable compared to that found for methane. As the number of diamond cages is increased, the distortion mechanism abruptly changes character. We have shown that the Stokes shift is size dependent and decreases with the number of diamond cages. If we neglect orbital symmetry effects on the optical excitations, the rate of decrease in the Stokes shift is, on average, 0.1 eV per cage for small diamondoids.

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Section: Methodsmentioning

confidence: 99%

Section: B Dmc Optical Gap Of Methane and Benchmarkingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Comparison of quantum Monte Carlo with time-dependent and static density-functional theory calculations of diamondoid excitation energies and Stokes shifts

2011

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Section: A Brief Description Of Diamondoidsmentioning

confidence: 99%

“…For example, rod-shaped diamondoids (with the shortest one being 1.0 nm long) and disc-shaped and screwshaped diamondoids (with different helical pitches and diameters) have been recognized [11]. For diamondoids and derivatives property predictions and characterizations in addition to variety of experimental techniques which are reported in [6] the quantum mechanical abinito methods are being utilized [12][13][14][15][16].Diamondoid-based derivatives are used to fight cancer, Alzheimer's disease as well as viral, bacterial, and parasital infectious diseases. Utilization of diamondoids in synthesis of high temperature polymers, in polymer nanocomposites, and in crystal engineering are some of their major applications in materials science.…”

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confidence: 99%

Diamondoids –The Molecular Lego of Biomedicine, Materials Science and Nanotechnology

Ali¹

2013

J Bioanal Biomed

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A Brief Description of DiamondoidsDiamondoids are a peculiar class of organic molecules with unique structures and properties. Diamondoid molecules (AKA polymantanes, adamantologs) are cage-like, ultra stable, saturated hydrocarbons. The basic repetitive unit of diamondoids is a ten-carbon tetracyclic cage system called "adamantane" (Figure 1a). Adamantane consists of cyclohexane rings in 'chair' conformation. These molecules are called "diamondoids" because their carbon-carbon framework is completely, or largely, superimposable on the diamond lattice ( Figure 2). Diamondoids show unique properties due to their exceptional atomic arrangements. The discovery of adamantane cage in 1933 [1] and its direct synthesis in 1957 [2] has turned this diamondoid and its derivatives into readily available compounds with numerous applications. Since 1960, the interest in practical applications of diamondoid molecules has steadily increased [3]. Diamondoids are presently molecular building blocks for biomedicine, materials science and nanotechnology that enable the design and manufacturing of nanometer-scale structures programmed to have virtually any desired shape and properties [4][5][6].Diamondoids were first discovered in petroleum [1] and since there has been limited progress in synthesizing them there have been continuous efforts in exploring them in petroleum and other fossil fuels [7][8][9][10]. The presence of diamondoids in fossil fuels has become much more than a chemical curiosity and has advanced to be a resourceful instrument in biomedicine, materials science, and nanotechnology [6].It has also been of major interest to discover the tremendous ways of derivativizing these molecules to do wonders in biomedicine, materials science and in the emerging field of nanotechnology [4][5][6]. The presence of chirality is an important feature in many diamondoids. The vast number of structural isomers and stereoisomers is another property of diamondoids. For instance, octamantane possesses hundreds of isomers in five molecular weight classes. The octamantane class with formula C 34 H 38 and molecular weight 446 has 18 chiral and achiral isomeric structures. Furthermore, there is unique and great geometric diversity within these isomers. For example, rod-shaped diamondoids (with the shortest one being 1.0 nm long) and disc-shaped and screwshaped diamondoids (with different helical pitches and diameters) have been recognized [11]. For diamondoids and derivatives property predictions and characterizations in addition to variety of experimental techniques which are reported in [6] the quantum mechanical abinito methods are being utilized [12][13][14][15][16].Diamondoid-based derivatives are used to fight cancer, Alzheimer's disease as well as viral, bacterial, and parasital infectious diseases. Utilization of diamondoids in synthesis of high temperature polymers, in polymer nanocomposites, and in crystal engineering are some of their major applications in materials science. Due to their six or more linking groups (Figure 3), di...

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Doped Diamondoids

2024

The Chemistry of Diamondoids

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Opto-electronic properties of adamantane and hydrogen-terminated sila- and germa-adamantane: A comparative study

Cited by 30 publications

References 35 publications

Comparison of quantum Monte Carlo with time-dependent and static density-functional theory calculations of diamondoid excitation energies and Stokes shifts

Comparison of quantum Monte Carlo with time-dependent and static density-functional theory calculations of diamondoid excitation energies and Stokes shifts

Diamondoids –The Molecular Lego of Biomedicine, Materials Science and Nanotechnology

Doped Diamondoids

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