The Experts below are selected from a list of 78 Experts worldwide ranked by ideXlab platform
Yia-chung Chang - One of the best experts on this subject based on the ideXlab platform.
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trion ground state excited states and absorption spectrum using electron exciton Basis
Physical Review B, 2012Co-Authors: Shiue-yuan Shiau, Monique Combescot, Yia-chung ChangAbstract:We solve the Schr\"odinger equation for two electrons plus one Hole by writing it in the electron-exciton Basis. One advantage of this Basis is to eliminate the exciton contribution from the trion energy in a natural way. The interacting electron-exciton system is treated using the recently developed composite boson many-body formalism, which allows an exact handling of electron exchange. We numerically solve the resulting electron-exciton Schr\"odinger equation with the exciton levels restricted to the lowest $1s,\phantom{\rule{0.28em}{0ex}}2s$, and $3s$ states, and we derive the trion ground-state energy as a function of the electron-to-Hole mass ratio. This restricted electron-Hole Basis already gives results in reasonable agreement with those obtained through the best variational methods using free carriers. The main advantage of the electron-Hole Basis is to allow us to reach the bound and unbound trion excited states as easily as the ground state. Through the trion wave functions, we also derive the optical absorption spectrum in the presence of hot carriers for two-dimensional quantum wells. We find large peaks located at the exciton levels, which are attributed to electron-exciton (unbound) scattering states, and small peaks identified with trion bound states.
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Trion ground state, excited states, and absorption spectrum using electron-exciton Basis
Physical Review B: Condensed Matter and Materials Physics, 2012Co-Authors: Shiue-yuan Shiau, Monique Combescot, Yia-chung ChangAbstract:We solve the Schrodinger equation for two electrons plus one Hole by writing it in the electron-exciton Basis. One advantage of this Basis is to eliminate the exciton contribution from the trion energy in a natural way. The interacting electron-exciton system is treated using the recently developed composite boson many-body formalism, which allows an exact handling of electron exchange. We numerically solve the resulting electron-exciton Schrodinger equation with the exciton levels restricted to the lowest 1s, 2s, and 3s states, and we derive the trion ground-state energy as a function of the electron-to-Hole mass ratio. This restricted electron-Hole Basis already gives results in reasonable agreement with those obtained through the best variational methods using free carriers. The main advantage of the electron-Hole Basis is to allow us to reach the bound and unbound trion excited states as easily as the ground state. Through the trion wave functions, we also derive the optical absorption spectrum in the presence of hot carriers for two-dimensional quantum wells. We find large peaks located at the exciton levels, which are attributed to electron-exciton (unbound) scattering states, and small peaks identified with trion bound states.
N Tachi - One of the best experts on this subject based on the ideXlab platform.
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Incidence of Reopening and Variables That Influence Reopening After Macular Hole Surgery
Japanese journal of ophthalmology, 2001Co-Authors: K Kumagai, N Ogino, S Demizu, K Atsumi, H Kurihara, M Iwaki, H Ishigooka, N TachiAbstract:Abstract Purpose: To evaluate the incidence and variables of reopening of macular Holes after macular Hole surgery. Methods: Our study included 467 eyes in which macular Holes were successfully closed after surgery. Surgical techniques consisted of conventional methods (358 eyes) and scalping methods (109 eyes) with retinal pigment scalping of the macular Hole Basis added in such cases: reoperation, Hole size (more than 0.4 disc diameter), duration of symptoms (more than 2 years). Long term incidence of reopening was predicted by life table method. After we compared reopened cases with non-reopened cases, the variables of gender, stage, biocular occurrence, age, duration of symptoms, Hole size, preoperative visual acuity, refraction axial length ratio, and intraoperative retinal tears were used for the multiple regression. Results: Reopening was found in 20 eyes (5.6%) treated by conventional methods and in 10 eyes (9.2%) treated by scalping methods. Survival ratio was 87% for the conventional methods in 6 years and 79% for the scalping methods in 5 years. The variables influencing reopening were as follows: conventional methods: gender ( r = 0.065, P = .19), biocular occurrence ( r = 0.12, P = .026), and refraction axial length ratio ( r = −0.11, P = .045); scalping methods: Hole size ( r = 0.14, P = .25). Conclusions: Incidence of reopening in scalping methods was high. The variables that influenced reopening after macular Hole surgery were biocular occurrence and refraction axial length ratio in conventional methods. The shape of the eye may be related to reopening.
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Variables that influence visual acuity after macular Hole surgery
Nippon Ganka Gakkai zasshi, 2000Co-Authors: K Kumagai, N Ogino, S Demizu, K Atsumi, H Kurihara, M Iwaki, H Ishigooka, N TachiAbstract:To evaluate the variables that influence visual acuity and visual improvement after macular Hole surgery. Our study included 421 eyes in which maculor Holes were successfully closed after surgery and followed up at least 1 year after the last surgery. Surgical techniques were conventional methods (Group 1: 350 eyes) with retinal pigment scalping of the macular Hole Basis added in the refractory cases (Group 2: 71 eyes). The variables used for the multiple regression were gender, age, preoperative visual acuity, Hole stage, duration of symptoms, Hole size, and axial length. The variables that most influenced postoperative visual acuity were as follows: Group 1: gender (r = -0.011, p = 0.016), age (r = -0.17, p = 0.005), preoperative visual acuity (r = 0.51, p < 0.0001), duration of symptoms (r = -0.015, p < 0.0001), and axial length (r = -0.090, p = 0.045). Group 2: age (r = -0.18, p = 0.047), and preoperative visual acuity (r = 0.47, p < 0.0001). The variables that influenced visual acuity and visual improvement after macular Hole surgery were common. In Group 1: gender, age, preoperative visual acuity, duration of symptoms, and axial length; in Group 2: age and preoperative visual acuity.
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Incidence of reopening and variables that influence reopening after macular Hole surgery
Nippon Ganka Gakkai zasshi, 2000Co-Authors: K Kumagai, N Ogino, S Demizu, K Atsumi, H Kurihara, M Iwaki, H Ishigooka, N TachiAbstract:To evaluate the incidence and variables of reopening of macular Holes after macular Hole surgery. Our study included 467 eyes in which maculor Holes were successfully closed after surgery. Surgical techniques consisted of conventional methods (358 eyes) and scalping methods (109 eyes) with retinal pigment scalping of the macular Hole Basis added in such cases: reoperation, Hole size (more than 0.4 disc diameter), duration of symptoms (more than 2 years). Long term incidence of reopening was predicted by life table method. After we compared reopened cases with non-reopened cases, the variables of gender, stage, biocular occurrence, age, duration of symptoms, Hole size, preoperative visual acuity, refraction axial length ratio, and intraoperative retinal tears were used for the multiple regression. Reopening was found in 20 eyes (5.6%) treated by conventional methods and in 10 eyes (9.2%) treated by scalping methods. Survival ratio was 87% for the conventional methods in 6 years and 79% for the scalping methods in 5 years. The variables influencing reopening were as follows: conventional methods: gender (r = 0.065, p = 0.19), biocular occurrence (r = 0.12, p = 0.026), and refraction axial length ratio (r = -0.11, p = 0.045); scalping methods: Hole size (r = 0.14, p = 0.25). Incidence of reopening in scalping methods was high. The variables that influenced reopening after macular Hole surgery were biocular occurrence and refraction axial length ratio in conventional methods. The shape of the eye may be related to reopening.
Shiue-yuan Shiau - One of the best experts on this subject based on the ideXlab platform.
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trion ground state excited states and absorption spectrum using electron exciton Basis
Physical Review B, 2012Co-Authors: Shiue-yuan Shiau, Monique Combescot, Yia-chung ChangAbstract:We solve the Schr\"odinger equation for two electrons plus one Hole by writing it in the electron-exciton Basis. One advantage of this Basis is to eliminate the exciton contribution from the trion energy in a natural way. The interacting electron-exciton system is treated using the recently developed composite boson many-body formalism, which allows an exact handling of electron exchange. We numerically solve the resulting electron-exciton Schr\"odinger equation with the exciton levels restricted to the lowest $1s,\phantom{\rule{0.28em}{0ex}}2s$, and $3s$ states, and we derive the trion ground-state energy as a function of the electron-to-Hole mass ratio. This restricted electron-Hole Basis already gives results in reasonable agreement with those obtained through the best variational methods using free carriers. The main advantage of the electron-Hole Basis is to allow us to reach the bound and unbound trion excited states as easily as the ground state. Through the trion wave functions, we also derive the optical absorption spectrum in the presence of hot carriers for two-dimensional quantum wells. We find large peaks located at the exciton levels, which are attributed to electron-exciton (unbound) scattering states, and small peaks identified with trion bound states.
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Trion ground state, excited states, and absorption spectrum using electron-exciton Basis
Physical Review B: Condensed Matter and Materials Physics, 2012Co-Authors: Shiue-yuan Shiau, Monique Combescot, Yia-chung ChangAbstract:We solve the Schrodinger equation for two electrons plus one Hole by writing it in the electron-exciton Basis. One advantage of this Basis is to eliminate the exciton contribution from the trion energy in a natural way. The interacting electron-exciton system is treated using the recently developed composite boson many-body formalism, which allows an exact handling of electron exchange. We numerically solve the resulting electron-exciton Schrodinger equation with the exciton levels restricted to the lowest 1s, 2s, and 3s states, and we derive the trion ground-state energy as a function of the electron-to-Hole mass ratio. This restricted electron-Hole Basis already gives results in reasonable agreement with those obtained through the best variational methods using free carriers. The main advantage of the electron-Hole Basis is to allow us to reach the bound and unbound trion excited states as easily as the ground state. Through the trion wave functions, we also derive the optical absorption spectrum in the presence of hot carriers for two-dimensional quantum wells. We find large peaks located at the exciton levels, which are attributed to electron-exciton (unbound) scattering states, and small peaks identified with trion bound states.
Daniel Sanchezportal - One of the best experts on this subject based on the ideXlab platform.
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cubic scaling iterative solution of the bethe salpeter equation for finite systems
Physical Review B, 2015Co-Authors: Mathias P Ljungberg, Daniel Sanchezportal, Peter Koval, Dietrich Foerster, Francesco FerrariAbstract:The Bethe-Salpeter equation (BSE) is currently the state of the art in the description of neutral electron excitations in both solids and large finite systems. It is capable of accurately treating charge-transfer excitations that present difficulties for simpler approaches. We present a local Basis set formulation of the BSE for molecules where the optical spectrum is computed with the iterative Haydock recursion scheme, leading to a low computational complexity and memory footprint. Using a variant of the algorithm we can go beyond the Tamm-Dancoff approximation (TDA). We rederive the recursion relations for general matrix elements of a resolvent, show how they translate into continued fractions, and study the convergence of the method with the number of recursion coefficients and the role of different terminators. Due to the locality of the Basis functions the computational cost of each iteration scales asymptotically as $O(N^3)$ with the number of atoms, while the number of iterations is typically much lower than the size of the underlying electron-Hole Basis. In practice we see that , even for systems with thousands of orbitals, the runtime will be dominated by the $O(N^2)$ operation of applying the Coulomb kernel in the atomic orbital representation
K Kumagai - One of the best experts on this subject based on the ideXlab platform.
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Incidence of Reopening and Variables That Influence Reopening After Macular Hole Surgery
Japanese journal of ophthalmology, 2001Co-Authors: K Kumagai, N Ogino, S Demizu, K Atsumi, H Kurihara, M Iwaki, H Ishigooka, N TachiAbstract:Abstract Purpose: To evaluate the incidence and variables of reopening of macular Holes after macular Hole surgery. Methods: Our study included 467 eyes in which macular Holes were successfully closed after surgery. Surgical techniques consisted of conventional methods (358 eyes) and scalping methods (109 eyes) with retinal pigment scalping of the macular Hole Basis added in such cases: reoperation, Hole size (more than 0.4 disc diameter), duration of symptoms (more than 2 years). Long term incidence of reopening was predicted by life table method. After we compared reopened cases with non-reopened cases, the variables of gender, stage, biocular occurrence, age, duration of symptoms, Hole size, preoperative visual acuity, refraction axial length ratio, and intraoperative retinal tears were used for the multiple regression. Results: Reopening was found in 20 eyes (5.6%) treated by conventional methods and in 10 eyes (9.2%) treated by scalping methods. Survival ratio was 87% for the conventional methods in 6 years and 79% for the scalping methods in 5 years. The variables influencing reopening were as follows: conventional methods: gender ( r = 0.065, P = .19), biocular occurrence ( r = 0.12, P = .026), and refraction axial length ratio ( r = −0.11, P = .045); scalping methods: Hole size ( r = 0.14, P = .25). Conclusions: Incidence of reopening in scalping methods was high. The variables that influenced reopening after macular Hole surgery were biocular occurrence and refraction axial length ratio in conventional methods. The shape of the eye may be related to reopening.
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Variables that influence visual acuity after macular Hole surgery
Nippon Ganka Gakkai zasshi, 2000Co-Authors: K Kumagai, N Ogino, S Demizu, K Atsumi, H Kurihara, M Iwaki, H Ishigooka, N TachiAbstract:To evaluate the variables that influence visual acuity and visual improvement after macular Hole surgery. Our study included 421 eyes in which maculor Holes were successfully closed after surgery and followed up at least 1 year after the last surgery. Surgical techniques were conventional methods (Group 1: 350 eyes) with retinal pigment scalping of the macular Hole Basis added in the refractory cases (Group 2: 71 eyes). The variables used for the multiple regression were gender, age, preoperative visual acuity, Hole stage, duration of symptoms, Hole size, and axial length. The variables that most influenced postoperative visual acuity were as follows: Group 1: gender (r = -0.011, p = 0.016), age (r = -0.17, p = 0.005), preoperative visual acuity (r = 0.51, p < 0.0001), duration of symptoms (r = -0.015, p < 0.0001), and axial length (r = -0.090, p = 0.045). Group 2: age (r = -0.18, p = 0.047), and preoperative visual acuity (r = 0.47, p < 0.0001). The variables that influenced visual acuity and visual improvement after macular Hole surgery were common. In Group 1: gender, age, preoperative visual acuity, duration of symptoms, and axial length; in Group 2: age and preoperative visual acuity.
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Incidence of reopening and variables that influence reopening after macular Hole surgery
Nippon Ganka Gakkai zasshi, 2000Co-Authors: K Kumagai, N Ogino, S Demizu, K Atsumi, H Kurihara, M Iwaki, H Ishigooka, N TachiAbstract:To evaluate the incidence and variables of reopening of macular Holes after macular Hole surgery. Our study included 467 eyes in which maculor Holes were successfully closed after surgery. Surgical techniques consisted of conventional methods (358 eyes) and scalping methods (109 eyes) with retinal pigment scalping of the macular Hole Basis added in such cases: reoperation, Hole size (more than 0.4 disc diameter), duration of symptoms (more than 2 years). Long term incidence of reopening was predicted by life table method. After we compared reopened cases with non-reopened cases, the variables of gender, stage, biocular occurrence, age, duration of symptoms, Hole size, preoperative visual acuity, refraction axial length ratio, and intraoperative retinal tears were used for the multiple regression. Reopening was found in 20 eyes (5.6%) treated by conventional methods and in 10 eyes (9.2%) treated by scalping methods. Survival ratio was 87% for the conventional methods in 6 years and 79% for the scalping methods in 5 years. The variables influencing reopening were as follows: conventional methods: gender (r = 0.065, p = 0.19), biocular occurrence (r = 0.12, p = 0.026), and refraction axial length ratio (r = -0.11, p = 0.045); scalping methods: Hole size (r = 0.14, p = 0.25). Incidence of reopening in scalping methods was high. The variables that influenced reopening after macular Hole surgery were biocular occurrence and refraction axial length ratio in conventional methods. The shape of the eye may be related to reopening.