The Experts below are selected from a list of 195 Experts worldwide ranked by ideXlab platform
Surya Chattopadhyaya - One of the best experts on this subject based on the ideXlab platform.
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modification of band gaps and optoelectronic properties of binary calcium chalcogenides by means of doping of Magnesium Atom s in rock salt phase a first principle based theoretical initiative
Journal of Solid State Chemistry, 2018Co-Authors: Bimal Debnath, Utpal Sarkar, Manish Debbarma, Rahul Bhattacharjee, Surya ChattopadhyayaAbstract:Abstract The band gaps and optoelectronic properties of binary calcium chalcogenide semiconductors have been modified theoretically by doping Magnesium Atom(s) into their respective rock-salt unit cells at some specific concentrations x = 0.0, 0.25, 0.50, 0.75 and 1.0 and confirmed such modifications by studying their structural, electronic and optical properties using DFT based FP-LAPW approach. The WC-GGA functional is used to calculate structural properties, while mBJ, B3LYP and WC-GGA are used for calculating electronic and optical properties. The concentration dependences of lattice parameter, bulk modulus and fundamental band gap for each alloy system exhibit nonlinearity. The Atomic and orbital origin of different electronic states in the band structure of each compound are explored from its density of states (DOS). The microscopic origin of band gap bowing for each of the alloy systems is explored in terms of volume deformation, charge exchange and structural relaxation. The chemical bonds between the constituent Atoms in each compound are found as ionic in nature. Optical properties of each specimen are calculated from its computed spectra of dielectric function, refractive index, extinction coefficient, normal incidence reflectivity, optical conductivity, optical absorption and energy loss function. Several calculated results have been compared with available experimental and other theoretical data.
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tuning of electronic band gaps and optoelectronic properties of binary strontium chalcogenides by means of doping of Magnesium Atom s a first principles based theoretical initiative with mbj b3lyp and wc gga functionals
Physica B-condensed Matter, 2018Co-Authors: Bimal Debnath, Utpal Sarkar, Manish Debbarma, Rahul Bhattacharjee, Surya ChattopadhyayaAbstract:Abstract First principle based theoretical initiative is taken to tune the optoelectronic properties of binary strontium chalcogenide semiconductors by doping Magnesium Atom(s) into their rock-salt unit cells at specific concentrations x = 0.0, 0.25, 0.50, 0.75 and 1.0 and such tuning is established by studying structural, electronic and optical properties of designed binary compounds and ternary alloys employing WC-GGA, B3LYP and mBJ exchange-correlation functionals. Band structure of each compound is constructed and respective band gaps under all the potential schemes are measured. The band gap bowing and its microscopic origin are calculated using quadratic fit and Zunger's approach, respectively. The Atomic and orbital origins of electronic states in the band structure of any compound are explored from its density of states. The nature of chemical bonds between the constituent Atoms in each compound is explored from the valence electron density contour plots. Optical properties of any specimen are explored from the computed spectra of its dielectric function, refractive index, extinction coefficient, normal incidence reflectivity, optical conductivity optical absorption and energy loss function. Several calculated results are compared with available experimental and earlier theoretical data.
Utpal Sarkar - One of the best experts on this subject based on the ideXlab platform.
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modification of band gaps and optoelectronic properties of binary calcium chalcogenides by means of doping of Magnesium Atom s in rock salt phase a first principle based theoretical initiative
Journal of Solid State Chemistry, 2018Co-Authors: Bimal Debnath, Utpal Sarkar, Manish Debbarma, Rahul Bhattacharjee, Surya ChattopadhyayaAbstract:Abstract The band gaps and optoelectronic properties of binary calcium chalcogenide semiconductors have been modified theoretically by doping Magnesium Atom(s) into their respective rock-salt unit cells at some specific concentrations x = 0.0, 0.25, 0.50, 0.75 and 1.0 and confirmed such modifications by studying their structural, electronic and optical properties using DFT based FP-LAPW approach. The WC-GGA functional is used to calculate structural properties, while mBJ, B3LYP and WC-GGA are used for calculating electronic and optical properties. The concentration dependences of lattice parameter, bulk modulus and fundamental band gap for each alloy system exhibit nonlinearity. The Atomic and orbital origin of different electronic states in the band structure of each compound are explored from its density of states (DOS). The microscopic origin of band gap bowing for each of the alloy systems is explored in terms of volume deformation, charge exchange and structural relaxation. The chemical bonds between the constituent Atoms in each compound are found as ionic in nature. Optical properties of each specimen are calculated from its computed spectra of dielectric function, refractive index, extinction coefficient, normal incidence reflectivity, optical conductivity, optical absorption and energy loss function. Several calculated results have been compared with available experimental and other theoretical data.
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tuning of electronic band gaps and optoelectronic properties of binary strontium chalcogenides by means of doping of Magnesium Atom s a first principles based theoretical initiative with mbj b3lyp and wc gga functionals
Physica B-condensed Matter, 2018Co-Authors: Bimal Debnath, Utpal Sarkar, Manish Debbarma, Rahul Bhattacharjee, Surya ChattopadhyayaAbstract:Abstract First principle based theoretical initiative is taken to tune the optoelectronic properties of binary strontium chalcogenide semiconductors by doping Magnesium Atom(s) into their rock-salt unit cells at specific concentrations x = 0.0, 0.25, 0.50, 0.75 and 1.0 and such tuning is established by studying structural, electronic and optical properties of designed binary compounds and ternary alloys employing WC-GGA, B3LYP and mBJ exchange-correlation functionals. Band structure of each compound is constructed and respective band gaps under all the potential schemes are measured. The band gap bowing and its microscopic origin are calculated using quadratic fit and Zunger's approach, respectively. The Atomic and orbital origins of electronic states in the band structure of any compound are explored from its density of states. The nature of chemical bonds between the constituent Atoms in each compound is explored from the valence electron density contour plots. Optical properties of any specimen are explored from the computed spectra of its dielectric function, refractive index, extinction coefficient, normal incidence reflectivity, optical conductivity optical absorption and energy loss function. Several calculated results are compared with available experimental and earlier theoretical data.
Rahul Bhattacharjee - One of the best experts on this subject based on the ideXlab platform.
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modification of band gaps and optoelectronic properties of binary calcium chalcogenides by means of doping of Magnesium Atom s in rock salt phase a first principle based theoretical initiative
Journal of Solid State Chemistry, 2018Co-Authors: Bimal Debnath, Utpal Sarkar, Manish Debbarma, Rahul Bhattacharjee, Surya ChattopadhyayaAbstract:Abstract The band gaps and optoelectronic properties of binary calcium chalcogenide semiconductors have been modified theoretically by doping Magnesium Atom(s) into their respective rock-salt unit cells at some specific concentrations x = 0.0, 0.25, 0.50, 0.75 and 1.0 and confirmed such modifications by studying their structural, electronic and optical properties using DFT based FP-LAPW approach. The WC-GGA functional is used to calculate structural properties, while mBJ, B3LYP and WC-GGA are used for calculating electronic and optical properties. The concentration dependences of lattice parameter, bulk modulus and fundamental band gap for each alloy system exhibit nonlinearity. The Atomic and orbital origin of different electronic states in the band structure of each compound are explored from its density of states (DOS). The microscopic origin of band gap bowing for each of the alloy systems is explored in terms of volume deformation, charge exchange and structural relaxation. The chemical bonds between the constituent Atoms in each compound are found as ionic in nature. Optical properties of each specimen are calculated from its computed spectra of dielectric function, refractive index, extinction coefficient, normal incidence reflectivity, optical conductivity, optical absorption and energy loss function. Several calculated results have been compared with available experimental and other theoretical data.
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tuning of electronic band gaps and optoelectronic properties of binary strontium chalcogenides by means of doping of Magnesium Atom s a first principles based theoretical initiative with mbj b3lyp and wc gga functionals
Physica B-condensed Matter, 2018Co-Authors: Bimal Debnath, Utpal Sarkar, Manish Debbarma, Rahul Bhattacharjee, Surya ChattopadhyayaAbstract:Abstract First principle based theoretical initiative is taken to tune the optoelectronic properties of binary strontium chalcogenide semiconductors by doping Magnesium Atom(s) into their rock-salt unit cells at specific concentrations x = 0.0, 0.25, 0.50, 0.75 and 1.0 and such tuning is established by studying structural, electronic and optical properties of designed binary compounds and ternary alloys employing WC-GGA, B3LYP and mBJ exchange-correlation functionals. Band structure of each compound is constructed and respective band gaps under all the potential schemes are measured. The band gap bowing and its microscopic origin are calculated using quadratic fit and Zunger's approach, respectively. The Atomic and orbital origins of electronic states in the band structure of any compound are explored from its density of states. The nature of chemical bonds between the constituent Atoms in each compound is explored from the valence electron density contour plots. Optical properties of any specimen are explored from the computed spectra of its dielectric function, refractive index, extinction coefficient, normal incidence reflectivity, optical conductivity optical absorption and energy loss function. Several calculated results are compared with available experimental and earlier theoretical data.
Jouko Korppi-tommola - One of the best experts on this subject based on the ideXlab platform.
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Spectroscopic properties of Mg-chlorin, Mg-porphin and chlorophylls a, b, c1, c2, c3 and d studied by semi-empirical and ab initio MO/CI methods
Physical Chemistry Chemical Physics, 2000Co-Authors: J. Linnanto, Jouko Korppi-tommolaAbstract:The semi-empirical and ab initio molecular orbital/configuration interaction (MO/CI) methods were used to study spectroscopic properties of chlorophylls a, b, c1, c2, c3 and d and Magnesium porphin and Magnesium chlorin. Energy minimisation at the PM3 level of all chlorophylls put the Magnesium Atom away from the centre and above the porphyrin ring and the Atomic charges on the nitrogen Atoms became positive. At the ab initio HF/6-31G* level of calculation the Magnesium is centrally located in the porphyrin plane and the Atomic charge on the Magnesium Atom is positive and that on the surrounding nitrogens negative. Three CI methods used, ZINDO/S CIS (15,15), PM3 CISD (5,5) and ab initio CIS (5,5)/6-31G*, obeyed linear correlation between the experimentally observed and calculated spectroscopic transition energies. The PM3 CISD (5,5) method gave best estimates of Qy, Qx and the Soret transition energies, but predicted oscillator strengths poorly. The ZINDO/S CIS (15,15) method gave best results in the overall simulation of the absorption spectra of chlorophylls, both intensities and wavelengths. The effect of solvent co-ordination on the excited states of chlorophyll a and chlorophyll b was also studied. Calculations predict solvent induced spectroscopic shifts of the Qx and Soret transitions but leave the Qy transition almost unshifted. This is a result of solvent-induced energy level shifts and charge redistribution on the Magnesium Atom of chlorophylls in the excited states. The results are discussed with reference to spectroscopic properties of chlorophylls in solution, chlorophylls in aggregates and in photosynthetic light-harvesting antenna.
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Spectroscopic properties of Mg-chlorin, Mg-porphin and chlorophylls a, b, c1, c2, c3and d studied by semi-empirical and ab initio MO/CI methods
Physical Chemistry Chemical Physics, 2000Co-Authors: J. Linnanto, Jouko Korppi-tommolaAbstract:The semi-empirical and ab initio molecular orbital/conÐguration interaction (MO/CI) methods were used to study spectroscopic properties of chlorophylls a, b, chlorin. Energy minimisation at the PM3 level of all chlorophylls put the Magnesium Atom away from the centre and above the porphyrin ring and the Atomic charges on the nitrogen Atoms became positive. At the ab initio HF/6-31G* level of calculation the Magnesium is centrally located in the porphyrin plane and the Atomic charge on the Magnesium Atom is positive and that on the surrounding nitrogens negative. Three CI methods used, ZINDO/S CIS (15,15), PM3 CISD (5,5) and ab initio CIS (5,5)/6-31G*, obeyed linear correlation between the experimentally observed and calculated spectroscopic transition energies. The PM3 CISD (5,5) method gave best estimates of c1, c2 , c3 Q and the Soret transition energies, but predicted oscillator strengths poorly. The ZINDO/S CIS (15,15) method gave best results in the overall simulation of the absorption spectra of chlorophylls, both intensities and wavelengths. The e†ect of solvent co-ordination on the excited states of chlorophyll a and chlorophyll b was also studied. Calculations predict solvent induced spectroscopic shifts of the and Soret transitions but leave the transition almost unshifted. This is a result of solvent-induced y,Qx energy level shifts and charge redistribution on the Magnesium Atom of chlorophylls in the excited states. The results are discussed with reference to spectroscopic properties of chlorophylls in solution, chlorophylls in aggregates and in photosynthetic light-harvesting antenna
Bimal Debnath - One of the best experts on this subject based on the ideXlab platform.
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modification of band gaps and optoelectronic properties of binary calcium chalcogenides by means of doping of Magnesium Atom s in rock salt phase a first principle based theoretical initiative
Journal of Solid State Chemistry, 2018Co-Authors: Bimal Debnath, Utpal Sarkar, Manish Debbarma, Rahul Bhattacharjee, Surya ChattopadhyayaAbstract:Abstract The band gaps and optoelectronic properties of binary calcium chalcogenide semiconductors have been modified theoretically by doping Magnesium Atom(s) into their respective rock-salt unit cells at some specific concentrations x = 0.0, 0.25, 0.50, 0.75 and 1.0 and confirmed such modifications by studying their structural, electronic and optical properties using DFT based FP-LAPW approach. The WC-GGA functional is used to calculate structural properties, while mBJ, B3LYP and WC-GGA are used for calculating electronic and optical properties. The concentration dependences of lattice parameter, bulk modulus and fundamental band gap for each alloy system exhibit nonlinearity. The Atomic and orbital origin of different electronic states in the band structure of each compound are explored from its density of states (DOS). The microscopic origin of band gap bowing for each of the alloy systems is explored in terms of volume deformation, charge exchange and structural relaxation. The chemical bonds between the constituent Atoms in each compound are found as ionic in nature. Optical properties of each specimen are calculated from its computed spectra of dielectric function, refractive index, extinction coefficient, normal incidence reflectivity, optical conductivity, optical absorption and energy loss function. Several calculated results have been compared with available experimental and other theoretical data.
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tuning of electronic band gaps and optoelectronic properties of binary strontium chalcogenides by means of doping of Magnesium Atom s a first principles based theoretical initiative with mbj b3lyp and wc gga functionals
Physica B-condensed Matter, 2018Co-Authors: Bimal Debnath, Utpal Sarkar, Manish Debbarma, Rahul Bhattacharjee, Surya ChattopadhyayaAbstract:Abstract First principle based theoretical initiative is taken to tune the optoelectronic properties of binary strontium chalcogenide semiconductors by doping Magnesium Atom(s) into their rock-salt unit cells at specific concentrations x = 0.0, 0.25, 0.50, 0.75 and 1.0 and such tuning is established by studying structural, electronic and optical properties of designed binary compounds and ternary alloys employing WC-GGA, B3LYP and mBJ exchange-correlation functionals. Band structure of each compound is constructed and respective band gaps under all the potential schemes are measured. The band gap bowing and its microscopic origin are calculated using quadratic fit and Zunger's approach, respectively. The Atomic and orbital origins of electronic states in the band structure of any compound are explored from its density of states. The nature of chemical bonds between the constituent Atoms in each compound is explored from the valence electron density contour plots. Optical properties of any specimen are explored from the computed spectra of its dielectric function, refractive index, extinction coefficient, normal incidence reflectivity, optical conductivity optical absorption and energy loss function. Several calculated results are compared with available experimental and earlier theoretical data.
