First-Principles Geometry Optimization of Polysilane

1988 ◽  
Vol 141 ◽  
Author(s):  
John W. Mintmire
Keyword(s):  
Total Energy ◽  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
Minimum Energy ◽  
Geometry Optimization ◽  
Functional Approach ◽  
Energy Structure ◽  
Atomic Orbitals ◽  
Local Density Functional

AbstractA first-principles approach is reviewed for calculating the total energy of chain polymers using a linear combination of atomic orbitals local-density functional approach. The geometry for the all-trans conformation of polysilane is optimized by finding the minimum energy structure using this method.

Boron Clusters in a Complex Defect in Silicon

1998 ◽  
Vol 510 ◽  
Author(s):  
M. Okamoto ◽  
K. Takayanagi ◽  
S. Takeda
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
Silicon Crystal ◽  
Functional Approach ◽  
The Other ◽  
Silicon Clusters ◽  
Boron Clusters ◽  
Complex Defect ◽  
Local Density Functional

AbstractWe have investigated stability of a new kind of boron clusters in silicon crystal using the first-principles local density functional approach. In the calculation, we used three types of hydrogenterminated silicon clusters; one of these types included the four interstitial cluster I4 as a complex defect. According to our calculation, we found that a new kind of boron clustering of n-borons substituted I4 (n < 3) became most stable when the ratio r = N(Bi) / (N(Sii) + N(Bi) in a confined area was less than or equal to 1/2, where N(B) is a number of interstitial boron atoms and N(Sii) is that of interstitial silicon atoms. On the other hand, when r was greater than 1/2, the l4 would be destroyed to create the [100] split boron pair, the [110] split silicon pair, and/or the substitutional boron and interstitial silicon pair.

Cubo-Octahedral B12 Clusters In Silicon Crystal

1996 ◽  
Vol 442 ◽  
Author(s):  
M. Okamoto ◽  
K. Hashimoto ◽  
K. Takayanagi
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
Silicon Crystal ◽  
Energy Difference ◽  
Functional Approach ◽  
Partial Density ◽  
Boron Clusters ◽  
Local Density Functional ◽  
Total Energy Difference

AbstractA new stable structure and the electronic structure of boron clusters in silicon crystal have been calculated using the first-principles local density functional approach for Si54B12H60 clusters. According to our calculation, the cubo-octahedral B12 cluster was found to be more stable than the icosahedral one proposed previously. The total energy difference was about 4.6 eV. The analysis of the partial density of states showed that the cubo-octahedral B12 cluster should act as a double acceptor.

Magnetic Properties of Embedded Rh Clusters in Ni Matrix

1995 ◽  
Vol 384 ◽  
Author(s):  
Zhi-Qiang Li ◽  
Yuichi Hashi ◽  
Jing-Zhi Yu ◽  
Kaoru Ohno ◽  
Yoshiyuki Kawazoe
Keyword(s):  
Magnetic Properties ◽  
Electronic Structure ◽  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
Magnetic Moments ◽  
Functional Formalism ◽  
Rhodium Clusters ◽  
Spin Polarized ◽  
Local Density Functional

ABSTRACTThe electronic structure and magnetic properties of rhodium clusters with sizes of 1 - 43 atoms embedded in the nickel host are studied by the first-principles spin-polarized calculations within the local density functional formalism. Single Rh atom in Ni matrix is found to have magnetic moment of 0.45μB. Rh13 and Rhl 9 clusters in Ni matrix have lower magnetic moments compared with the free ones. The most interesting finding is tha.t Rh43 cluster, which is bulk-like nonmagnetic in vacuum, becomes ferromagnetic when embedded in the nickel host.

Conformation and electronic structure of Carbidopa. A QM/MD study

2016 ◽  
Vol 15 (01) ◽  
pp. 1650002
Author(s):  
Ghader M. Sukker ◽  
Nuha Wazzan ◽  
Ashour Ahmed ◽  
Rifaat Hilal
Keyword(s):  
Density Functional ◽  
Minimum Energy ◽  
Geometry Optimization ◽  
Md Simulations ◽  
Energy Structure ◽  
Functional Theory ◽  
Conformational Preferences ◽  
The Density Functional Theory ◽  
Quantum Chemical Topology ◽  
Bonding Characteristics

Carbidopa (CD) is a drug used in combination with L-dopa (LD) in treatment of Parkinson’s disease (PD). CD is an inhibitor for enzyme decarboxylase, yet its mode of action is not entirely known although it is believed to involve enzyme shape recognition. The present work attempts to investigate the conformational preferences of CD. Tight geometry optimization at the density functional theory (DFT)/B3LYP/6-311[Formula: see text]G** level of theory has been carried out. The shallow nature of the potential energy surface (PES) and the presence of several local minima within a small energy range necessitate the launching of DFT-based molecular dynamics (MD) simulations. Two MD experiments were submitted for 35,000 points each. The complete trajectory in time domain of 10.5 ps is analyzed and discussed. The global minimum energy structure of CD is localized and identified by subsequent frequency calculations. The quantum theory of atom in molecules (QTAIMs) is used to extract and compare the quantum chemical topology features of the electron density distribution in CD and LD. Bonding characteristics are analyzed and discussed within the natural bond orbital (NBO) framework.

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