Academic literature on the topic 'KS-DFT'

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Journal articles on the topic "KS-DFT"

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Li, Hong Zhi, Lin Li, Zi Yan Zhong, Yi Han, LiHong Hu, and Ying Hua Lu. "An Accurate and Efficient Method to Predict Y-NO Bond Homolysis Bond Dissociation Energies." Mathematical Problems in Engineering 2013 (2013): 1–10. http://dx.doi.org/10.1155/2013/860357.

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The paper suggests a new method that combines the Kennard and Stone algorithm (Kenstone, KS), hierarchical clustering (HC), and ant colony optimization (ACO)-based extreme learning machine (ELM) (KS-HC/ACO-ELM) with the density functional theory (DFT) B3LYP/6-31G(d) method to improve the accuracy of DFT calculations for the Y-NO homolysis bond dissociation energies (BDE). In this method, Kenstone divides the whole data set into two parts, the training set and the test set; HC and ACO are used to perform the cluster analysis on molecular descriptors; correlation analysis is applied for selecting the most correlated molecular descriptors in the classes, and ELM is the nonlinear model for establishing the relationship between DFT calculations and homolysis BDE experimental values. The results show that the standard deviation of homolysis BDE in the molecular test set is reduced from 4.03 kcal mol−1calculated by the DFT B3LYP/6-31G(d) method to 0.30, 0.28, 0.29, and 0.32 kcal mol−1by the KS-ELM, KS-HC-ELM, and KS-ACO-ELM methods and the artificial neural network (ANN) combined with KS-HC, respectively. This method predicts accurate values with much higher efficiency when compared to the larger basis set DFT calculation and may also achieve similarly accurate calculation results for larger molecules.
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Fu, Zhiqiang, Lili Yang, Dongru Sun, Zexing Qu, Yufen Zhao, Jiali Gao, and Yong Wang. "Coupled electron and proton transfer in the piperidine drug metabolism pathway by the active species of cytochromes P450." Dalton Transactions 49, no. 32 (2020): 11099–107. http://dx.doi.org/10.1039/c9dt03056e.

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Ranasinghe, Duminda S., Ajith Perera, and Rodney J. Bartlett. "A note on the accuracy of KS-DFT densities." Journal of Chemical Physics 147, no. 20 (November 28, 2017): 204103. http://dx.doi.org/10.1063/1.5001939.

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Zhao, Yifen, Decong Li, and Zuming Liu. "A DFT study of pressure-induced phase transitions, structural and electronic properties of Cu2ZnSnS4." Modern Physics Letters B 30, no. 16 (June 20, 2016): 1650176. http://dx.doi.org/10.1142/s0217984916501761.

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The structural properties, phase transitions, and electronic structures of Cu2ZnSnS4 (CZTS) in the three structures have been researched using the first-principles density functional theory (DFT). The results indicate that the energies of stannite (ST) and pre-mixed Cu–Au (PMCA) CZTS are higher than those of kesterite (KS) CZTS, indicating that the KS CZTS is more stable. We found the phase transition pressure between the KS and ST structures of CZTS is about 32 GPa. Moreover, for KS- and PMCA-CZTS, there exists in the mischcrystal phase between 52 GPa and 65 GPa. The band structures show that the KS- and ST-CZTS are direct band gap semiconductors. The band gaps of three-type CZTS increase with increasing pressure, and the maximum band gap of KS and ST structures for CZTS occurs at 50 GPa. However, PMCA CZTS possesses metal property. Furthermore, the PMCA CZTS translates from metal to the indirect semiconductor with increasing pressure. The results play an important role in future experimental and theoretical work for CZTS materials.
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Mostafanejad, Mohammad, Jessica Haney, and A. Eugene DePrince. "Kinetic-energy-based error quantification in Kohn–Sham density functional theory." Physical Chemistry Chemical Physics 21, no. 48 (2019): 26492–501. http://dx.doi.org/10.1039/c9cp04595c.

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Yepes, Diana, Joel Valenzuela, Jorge I. Martínez-Araya, Patricia Pérez, and Pablo Jaque. "Effect of the exchange–correlation functional on the synchronicity/nonsynchronicity in bond formation in Diels–Alder reactions: a reaction force constant analysis." Physical Chemistry Chemical Physics 21, no. 14 (2019): 7412–28. http://dx.doi.org/10.1039/c8cp02284d.

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The performance of 24 KS-DFT-based methods (GGA, MGGA, HGGA, HMGGA, and DHGGA) was assessed, finding that M11 and M06-2X (HMGGA) predicting reliable TS geometries, energetics, and (a)synchronicities in Diels–Alder reactions.
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Chávez, Victor H., and Adam Wasserman. "Towards a density functional theory of molecular fragments. What is the shape of atoms in molecules?" Revista de la Academia Colombiana de Ciencias Exactas, Físicas y Naturales 44, no. 170 (March 16, 2020): 269–79. http://dx.doi.org/10.18257/raccefyn.960.

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In some sense, quantum mechanics solves all the problems in chemistry: The only thing one has to do is solve the Schrödinger equation for the molecules of interest. Unfortunately, the computational cost of solving this equation grows exponentially with the number of electrons and for more than ~100 electrons, it is impossible to solve it with chemical accuracy (~ 2 kcal/mol). The Kohn-Sham (KS) equations of density functional theory (DFT) allow us to reformulate the Schrödinger equation using the electronic probability density as the central variable without having to calculate the Schrödinger wave functions. The cost of solving the Kohn-Sham equations grows only as N3, where N is the number of electrons, which has led to the immense popularity of DFT in chemistry. Despite this popularity, even the most sophisticated approximations in KS-DFT result in errors that limit the use of methods based exclusively on the electronic density. By using fragment densities (as opposed to total densities) as the main variables, we discuss here how new methods can be developed that scale linearly with N while providing an appealing answer to the subtitle of the article: What is the shape of atoms in molecules?
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Schäffer, Claus E., and Jesper Bendix. "Kohn–Sham DFT and ligand-field theory — Is there a synergy?" Canadian Journal of Chemistry 87, no. 10 (October 2009): 1302–12. http://dx.doi.org/10.1139/v09-061.

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In forming electronic states of the partially filled shell of transition-metal atomic and molecular systems, real, symmetry-based, fixed, Kohn–Sham eigenorbitals can be used to bridge KS-states with strong-field, ligand-field states. Thereby, DFT computations, restrained by the use of these frozen orbitals of the so-called average-of-configuration type, allow a central-field modeling of the partially filled shell whose Hamiltonian matrix consists of mutually orthogonal diagonal and non-diagonal parts, of which only the former can be computed. Mutually orthogonal operators of ligand-field theory are particularly suited to parameterize the energy “data” obtained from the bridges between molecular Kohn–Sham DFT states and ligand-field states. With the d2 configuration as the simplest example encompassing both ligand-field and interelectronic repulsion, each one-electron parameter, though defined by energy differences of perturbed d orbitals, is associated with a 45 × 45, diagonal, theoretical, strong-field-type coefficient matrix of the ligand field repulsion model (LFR), which is mapped in a one-to-one fashion onto a likewise diagonal KS-DFT computational energy matrix. For sets of mutually orthogonal operators, the mapping determines the value of any such ligand-field parameter as a scalar product between the DFT matrix and the coefficient matrix of the associated ligand-field operator. Each and every two-electron parameter of LFR is in the same strong-field function basis associated with a 45 × 45 coefficient matrix that includes a non-diagonal part. This matrix, nevertheless, by the formation of a scalar product with the appropriate diagonal, computational DFT matrix, provides the value of the two-electron parameter. In spite of the lacking non-diagonal DFT information, its non-diagonal elements of the two-electron interelectronic repulsion matrices are indirectly accessible through the parameterization based upon the computed diagonal DFT matrices combined with the mapping of the DFT energy results onto the parametric LFR. In this way, LFR delivers back to DFT a quantification of the deviation of the systems’ eigenbasis from the DFT-computed states, which are defined by having unit occupation numbers. This work focuses firstly on using the LFR model for forming a full DFT energy matrix and dissecting it into mutually orthogonal one- and two-electron parts and secondly on the use of the two-electron parts to obtain a complete ligand-field image of a nephelauxetic, molecular atom, intrinsic of the chemical system.
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Elstner, Marcus, and Gotthard Seifert. "Density functional tight binding." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 372, no. 2011 (March 13, 2014): 20120483. http://dx.doi.org/10.1098/rsta.2012.0483.

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This paper reviews the basic principles of the density-functional tight-binding (DFTB) method, which is based on density-functional theory as formulated by Hohenberg, Kohn and Sham (KS-DFT). DFTB consists of a series of models that are derived from a Taylor series expansion of the KS-DFT total energy. In the lowest order (DFTB1), densities and potentials are written as superpositions of atomic densities and potentials. The Kohn–Sham orbitals are then expanded to a set of localized atom-centred functions, which are obtained for spherical symmetric spin-unpolarized neutral atoms self-consistently. The whole Hamilton and overlap matrices contain one- and two-centre contributions only. Therefore, they can be calculated and tabulated in advance as functions of the distance between atomic pairs. The second contributions to DFTB1, the DFT double counting terms, are summarized together with nuclear repulsion energy terms and can be rewritten as the sum of pairwise repulsive terms. The second-order (DFTB2) and third-order (DFTB3) terms in the energy expansion correspond to a self-consistent representation, where the deviation of the ground-state density from the reference density is represented by charge monopoles only. This leads to a computationally efficient representation in terms of atomic charges (Mulliken), chemical hardness (Hubbard) parameters and scaled Coulomb laws. Therefore, no additional adjustable parameters enter the DFTB2 and DFTB3 formalism. The handling of parameters, the efficiency, the performance and extensions of DFTB are briefly discussed.
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Malvaldi, Marco, Samantha Bruzzone, Cinzia Chiappe, Sergey Gusarov, and Andriy Kovalenko. "Ab Initio Study of Ionic Liquids by KS-DFT/3D-RISM-KH Theory." Journal of Physical Chemistry B 113, no. 11 (March 19, 2009): 3536–42. http://dx.doi.org/10.1021/jp810887z.

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Dissertations / Theses on the topic "KS-DFT"

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Baniahmad, Ata. "QUANTUM MECHANICAL Study and Modelling of MOLECULAR ELECTRONIC DEVICES." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/13193/.

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Molecular electronics pursues the use of molecules as fundamental electronic components. The inherent properties of molecules such as nano-size, low cost, scalability, and self-assembly are seen by many as a perfect complement to conventional silicon electronics. Molecule based electronics has captured the attention of a broad cross section of the scientific community. In molecular electronic devices, the possibility of having channels that are just one atomic layer thick, is perhaps the most attractive feature that takes the attention to graphene.The conductivity, stability, uniformity, composition, and 2D nature of graphene make it an excellent material for electronic devices. In this thesis we focused on Zigzag Graphene NanoRibbon(ZGNR) as a transmission channel. Due to the importance of an accurate description of the quantum effects in the operation of graphene devices, a full-quantum transport model has been adopted: the electron dynamics has been described by Density Functional Theory(DFT) and transport has been solved within the formalism of Non-Equilibrium Green’s Functions (NEGF). Using DFT and NEGF methods, the transport properties of ZGNR and ZGNR doped with Si are studied by systematically computing the transmission spectrum. It is observed that Si barrier destroyed the electronic transport properties of ZGNR, an energy gap appeared for ZGNR, and variations from conductor to semiconductor are displayed. Its followed by a ZGNR grown on a SiO2 crystal substrate, while substituting the Graphene electrodes with the Gold ones, and its effect on transmission properties have been studied. Improvement in transmission properties observed due to the formation of C-O bonds between ZGNR and substrate that make the ZGNR corrugated. Finally, we modeled a nano-scale Field Effect Transistor by implementing a gate under SiO2 substrate. A very good I-ON/I-OFF ratio has been observed although the device thickness.
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Conference papers on the topic "KS-DFT"

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Burnett, Sarah C., Daniel G. Sheppard, Kevin G. Honnell, and Travis Sjostrom. "Sesame-style decomposition of KS-DFT molecular dynamics for direct interrogation of nuclear models." In SHOCK COMPRESSION OF CONDENSED MATTER - 2017: Proceedings of the Conference of the American Physical Society Topical Group on Shock Compression of Condensed Matter. Author(s), 2018. http://dx.doi.org/10.1063/1.5044771.

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