Arijit Ghoshal - Academia.edu (original) (raw)

Papers by Arijit Ghoshal

Few-body systems, Jun 3, 2024

Few-body Systems, Sep 15, 2021

The effects of quantum plasma on the dynamics of positron scattering from the ground state of alk... more The effects of quantum plasma on the dynamics of positron scattering from the ground state of alkali atoms (lithium, sodium and potassium atoms) have been studied within the framework of a two-state approximation which incorporates the elastic channel and the positronium formation channel. Exponential cosine screened Coulomb potential is considered as the effective potential for the description of the quantum plasma. The ground state wave function and energy of the alkali atoms are calculated quite accurately by resorting to the 'method of model potential' and variational principle. The changes introduced by the quantum plasma in the differential and the total cross sections for the elastic and rearrangement scattering have been studied in details for the incident positron energy varying from 10 to 500 eV. It is observed that the varying screening strength of the background plasma causes appreciable changes in the cross sections.

Authorea, Feb 25, 2020

The stability of positronium negative ion embedded in non-ideal classical plasmas has been invest... more The stability of positronium negative ion embedded in non-ideal classical plasmas has been investigated theoretically within the framework of Rayleigh-Ritz variational method by computing its ground state energy quite accurately. A pseudopotential, derived from a solution of Bogolyubov's hierarchy equations, has been used to describe interactions among the charged particles in plasma. A large basis set is utilized to compute accurately various quantities, such as binding energy, cusp values, annihilation rate, associated with the ground state of the ion. A detailed study has been made on the effects of non-ideality of plasma on those quantities. In particular, special emphasis is given to determine the ranges of plasma screening parameters within which the ion remains stable.

Chinese Journal of Physics, Oct 1, 2016

Abstract 1 s → nlm excitations of hydrogen, for arbitrary n, l, m , by electron impact have been ... more Abstract 1 s → nlm excitations of hydrogen, for arbitrary n, l, m , by electron impact have been investigated within the framework of second-order Born approximation in the momentum space by taking into account the effect of exchange. Scattering amplitude has been derived in a closed form. We have made a detailed study on the total cross sections for intermediate and high energies of the incident electron. A simple law has been presented for obtaining asymptotic cross sections for excitation into different angular momentum states.

Physics of Plasmas, Feb 1, 2021

The scattering of slow electrons from the hydrogen atom embedded in non-ideal classical plasma ha... more The scattering of slow electrons from the hydrogen atom embedded in non-ideal classical plasma has been investigated by using the effective range theory. A pseudopotential, which has been derived from a solution of Bogolyubov's hierarchy equations, is used to represent the interactions among the charged particles in plasma. A detailed study is made on the effects of non-ideality of plasma on the scattering dynamics for a wide range of the non-ideality parameter. In particular, the zero-energy resonance phenomenon has been studied in detail by evaluating the singlet scattering length. It is found that the scattering length suffers significant changes when the non-ideality parameter approaches its critical value.

Journal of Physics B, Aug 26, 2008

ABSTRACT Positronium (Ps) formation in an arbitrary s-state from an arbitrary s-state of the hydr... more ABSTRACT Positronium (Ps) formation in an arbitrary s-state from an arbitrary s-state of the hydrogen atom by positron impact has been studied within the framework of distorted-wave theory (DWT) which has recently been derived by the authors. A general formula for obtaining partial-wave distorted-wave amplitudes of positronium formation for all such reactions has been derived in closed analytic forms. This general formalism has then been used to obtain the results for differential and total cross sections in the energy range 20–300 eV. Further, in order to derive the general formula for scattering amplitudes in a closed analytic form, a simple prescription has been made to evaluate the arbitrary order derivatives of the general three- denominator Lewis integral. To the best of our knowledge, the distorted-wave results for the differential and total cross sections for such reactions are reported for the first time in the literature.

Physical Review A, 2005

The scattering amplitude for positron-hydrogen collisions has been conveniently derived within th... more The scattering amplitude for positron-hydrogen collisions has been conveniently derived within the framework of distorted-wave theory by approximating the distortion potential in a particular channel as the average of perturbation of that particular channel over the bound states. A real advantage of this method is that a few straightforward calculations yield the expression of scattering amplitude as a function of partial wave. The method has been successfully applied to study 1s-2s excitation of hydrogen atom by positron impact and Ps ͑ns͒ ͑n = 1,2,3͒ formation in positron-hydrogen collisions in the intermediate and high energy range. Further to bring the scattering amplitudes in tracktable forms we have formulated an effective and efficient method for evaluating general three-denominator Lewis integral. The results compare nicely with other theoretical and experimental results available in the literature.

Physical Review A, Oct 14, 2005

Research Interests  Atomic & Molecular collisions.  Atomic collisions in plasmas.  Atomic and ... more Research Interests  Atomic & Molecular collisions.  Atomic collisions in plasmas.  Atomic and Molecular structure in plasmas.  Interaction of positron and positronium with atoms.  Atoms in external electric and magnetic fields.  Mathematical physics.

Chinese Journal of Physics, Jun 1, 2021

Abstract The dynamics of positron scattering from the ground state of lithium, sodium and potassi... more Abstract The dynamics of positron scattering from the ground state of lithium, sodium and potassium atoms in hot and dense plasmas has been investigated by applying a two-state approximation that includes elastic scattering and rearrangement scattering. The wave functions and energies of the target alkali atoms have been determined quite accurately within the framework of the ’method of model potential’. An inclusive study was made on the effects of plasma screening on the differential and total cross sections for elastic scattering and positronium formation in the ground state for the incident positron energy lying within 10 eV to 500 eV. For the unscreened case, our present results agree reasonably with the results of other calculations. It was found that the cross sections suffer considerable change due to the effects of the background plasma.

Physical Review A, Oct 14, 2005

A detailed study is made of the elastic differential cross section in positron-hydrogen collision... more A detailed study is made of the elastic differential cross section in positron-hydrogen collisions using the accurate Schwinger variational results for partial waves up to l = 19 of the preceding paper ͓Ghoshal and Mandal, Phys. Rev. A, 72, 042709 ͑2005͔͒. Dramatic behavior of the differential cross section is evident in the surface plots, suggesting interference of partial-wave contributions at small and large scattering angles for the appearance of rich structure. It is found that the behavior of the critical point basically characterizes the nature of the differential cross section. Further interferences of the scattered waves for different angular momentum states produced by the interaction between the incoming positron and the target hydrogen atom determine such behavior and consequently build up the nature of the differential cross section. These findings reveal the remarkable fact that positron-hydrogen scattering almost does not occur in the direction around 87.3°at an incident energy of about 3.4 eV, corresponding to incident positron momentum of 0.5 atomic units.

Physical Review A, Sep 14, 2005

The scattering amplitude for positron-hydrogen collisions has been conveniently derived within th... more The scattering amplitude for positron-hydrogen collisions has been conveniently derived within the framework of distorted-wave theory by approximating the distortion potential in a particular channel as the average of perturbation of that particular channel over the bound states. A real advantage of this method is that a few straightforward calculations yield the expression of scattering amplitude as a function of partial wave. The method has been successfully applied to study 1s-2s excitation of hydrogen atom by positron impact and Ps ͑ns͒ ͑n = 1,2,3͒ formation in positron-hydrogen collisions in the intermediate and high energy range. Further to bring the scattering amplitudes in tracktable forms we have formulated an effective and efficient method for evaluating general three-denominator Lewis integral. The results compare nicely with other theoretical and experimental results available in the literature.

Physica Scripta, 2003

Two types of correlated wavefunctions are considered for the ground state of helium iso-electroni... more Two types of correlated wavefunctions are considered for the ground state of helium iso-electronic systems in the forms in a.u.: (a) C ¼ P c i r li 1 r mi 2 r ni 12 exp½ÀðAr 1 þ Br 2 þ m i r 12 Þ þ ð1 *) 2Þ, and (b) C ¼ P c i r li 1 r mi 2 r ni 12 exp½ÀAðr 1 þ r 2 Þ=ða þ br 12 Þ m0 þ ð1 *) 2Þ; where l þ m þ n oðintegerÞ, and m 0 ¼ 1 2 ; 3 2 ;... Several wavefunctions, starting from the smallest number of terms, are reported in this work.The sets of the exponential correlation parameter m i and the inverse correlation parameter b are optimized by the Monte-Carlo method along with the other nonlinear variation parameters A; B to obtain quite accurate eigenenergies. At most a total number of 14 terms of type (a) and 25 terms of type (b) are required to obtain results in close agreement with the non-relativistic limits for all the systems. These values are compared with the results available in the literature.

Journal of Physics B, Mar 16, 2017

European Physical Journal D, Sep 1, 2017

Effects of nonideality of classical plasma on the reaction: p + H(1s) → H(nlm) + p has been inves... more Effects of nonideality of classical plasma on the reaction: p + H(1s) → H(nlm) + p has been investigated by carrying out fully quantum mechanical calculations within the framework of a first-order distorted wave method. Scattering amplitude is calculated conveniently by employing a simple, variationally determined wave function of hydrogen atom embedded in nonideal classical plasma. A detailed study is made on the changes in electron transfer cross sections due to the nonideality of plasma varying from 0 to 4 and the incident proton energy lying between 10 and 500 keV. It has been found that nonideality of plasma causes substantial change in capture cross section.

Modern Physics Letters B, Jun 30, 2023

In this paper, the effects of plasmas on the S-wave resonance states in the positron-potassium sy... more In this paper, the effects of plasmas on the S-wave resonance states in the positron-potassium system are investigated. Two different plasma conditions are considered, namely weakly coupled classical plasma (WCCP) and dense quantum plasma (DQP). The effective interaction potential in WCCP and DQP has been described by the Debye–Hückel model (static screened Coulomb potential) and a modified version of Debye–Hückel model (exponential cosine screened potential). Resonance parameters are determined by calculating the energy-density within the framework of the stabilization method. For the plasma-free case, three states, lying below the Ps[Formula: see text] threshold, are identified. The energy and the width agree well with the existing results in the literature. A detailed study is carried out to explore the changes emerging in the resonance parameters due to screening effects of WCCP and DQP. It is found that the energies of the three states are gradually pushed toward the Ps[Formula: see text] threshold due to the increasing plasma screening strength, whereas widths of the states vary differently.

Chinese Journal of Physics, Dec 1, 2010

Elastic scattering of low-energy electrons from the ground state of hydrogen atoms in dense quant... more Elastic scattering of low-energy electrons from the ground state of hydrogen atoms in dense quantum plasma environments has been studied using an effective range theory. We use the exponential cosine-screened Coulomb potential (ECSCP) to represent the plasma screening effect in a dense quantum plasma. Highly correlated Hylleraas-type wave functions for H(superscript -) are used to determine the effective range of the ion states. The results for S-wave singlet phase shifts in dense quantum plasmas are reported for the incident electron energy in the range for which only the elastic channel is open. Furthermore, we have compared the plasma screening effect of a dense quantum plasma with that of a weakly-coupled plasma, for which the plasma screening effect has been represented by the Debye model. Our results for the unscreened case agree nicely with some of the most accurate results available in the literature.

Chinese Journal of Physics, Oct 1, 2021

Abstract Effects of the hot and dense plasma on the doubly excited states (DES) of the four-elect... more Abstract Effects of the hot and dense plasma on the doubly excited states (DES) of the four-electron beryllium-like ions (BLI) with Z varying from 4 to 10 have been investigated by applying the stabilization method. The Debye–Huckel model has been used to describe the effective potential in the plasma. The four-electron ions are treated as an effective three-body problem by means of the method of model potential. One, four and five DESs lying above the 1s 2 2p threshold are found to exist in the ions having Z = 4 , Z = 5 and Z = 6 − 10 respectively. For the plasma-free case our results for the energy and width of the DESs are in agreement with the available results in the literature. A detailed study is made on the changes of energy and width of the DESs of the ions with varying plasma screening strength. Particular emphasis is given to explore the effects of the plasma on the whole sequence of ions.

Journal of Physics B, May 19, 2010

Bulletin of the American Physical Society, May 21, 2009

−λr cos(λr) (in a.u.), where r denotes the inter-particle distance. Within the framework of Ritz'... more −λr cos(λr) (in a.u.), where r denotes the inter-particle distance. Within the framework of Ritz's variational principle and making use of a highly correlated wave function, we have determined the ground state energies and wave functions of the helium atom for different values of the screening parameterλ. Furthermore, we have shown that the ground state energy of helium for a particular value of λ does converge with increasing number of terms in the wave function. In addition, using the stabilization method, we have investigated the doubly excited 2s 2 1 S e resonance state in helium with ECSCP. Resonance energy and width for various λ values are calculated. Our present work will play a useful role in the investigations of atomic structures in quantum plasmas [1]. [1]. P.K. Shukla and B.

Physical Review E, Jan 20, 2010

Few-body systems, Jun 3, 2024

Few-body Systems, Sep 15, 2021

The effects of quantum plasma on the dynamics of positron scattering from the ground state of alk... more The effects of quantum plasma on the dynamics of positron scattering from the ground state of alkali atoms (lithium, sodium and potassium atoms) have been studied within the framework of a two-state approximation which incorporates the elastic channel and the positronium formation channel. Exponential cosine screened Coulomb potential is considered as the effective potential for the description of the quantum plasma. The ground state wave function and energy of the alkali atoms are calculated quite accurately by resorting to the 'method of model potential' and variational principle. The changes introduced by the quantum plasma in the differential and the total cross sections for the elastic and rearrangement scattering have been studied in details for the incident positron energy varying from 10 to 500 eV. It is observed that the varying screening strength of the background plasma causes appreciable changes in the cross sections.

Authorea, Feb 25, 2020

The stability of positronium negative ion embedded in non-ideal classical plasmas has been invest... more The stability of positronium negative ion embedded in non-ideal classical plasmas has been investigated theoretically within the framework of Rayleigh-Ritz variational method by computing its ground state energy quite accurately. A pseudopotential, derived from a solution of Bogolyubov's hierarchy equations, has been used to describe interactions among the charged particles in plasma. A large basis set is utilized to compute accurately various quantities, such as binding energy, cusp values, annihilation rate, associated with the ground state of the ion. A detailed study has been made on the effects of non-ideality of plasma on those quantities. In particular, special emphasis is given to determine the ranges of plasma screening parameters within which the ion remains stable.

Chinese Journal of Physics, Oct 1, 2016

Abstract 1 s → nlm excitations of hydrogen, for arbitrary n, l, m , by electron impact have been ... more Abstract 1 s → nlm excitations of hydrogen, for arbitrary n, l, m , by electron impact have been investigated within the framework of second-order Born approximation in the momentum space by taking into account the effect of exchange. Scattering amplitude has been derived in a closed form. We have made a detailed study on the total cross sections for intermediate and high energies of the incident electron. A simple law has been presented for obtaining asymptotic cross sections for excitation into different angular momentum states.

Physics of Plasmas, Feb 1, 2021

The scattering of slow electrons from the hydrogen atom embedded in non-ideal classical plasma ha... more The scattering of slow electrons from the hydrogen atom embedded in non-ideal classical plasma has been investigated by using the effective range theory. A pseudopotential, which has been derived from a solution of Bogolyubov's hierarchy equations, is used to represent the interactions among the charged particles in plasma. A detailed study is made on the effects of non-ideality of plasma on the scattering dynamics for a wide range of the non-ideality parameter. In particular, the zero-energy resonance phenomenon has been studied in detail by evaluating the singlet scattering length. It is found that the scattering length suffers significant changes when the non-ideality parameter approaches its critical value.

Journal of Physics B, Aug 26, 2008

ABSTRACT Positronium (Ps) formation in an arbitrary s-state from an arbitrary s-state of the hydr... more ABSTRACT Positronium (Ps) formation in an arbitrary s-state from an arbitrary s-state of the hydrogen atom by positron impact has been studied within the framework of distorted-wave theory (DWT) which has recently been derived by the authors. A general formula for obtaining partial-wave distorted-wave amplitudes of positronium formation for all such reactions has been derived in closed analytic forms. This general formalism has then been used to obtain the results for differential and total cross sections in the energy range 20–300 eV. Further, in order to derive the general formula for scattering amplitudes in a closed analytic form, a simple prescription has been made to evaluate the arbitrary order derivatives of the general three- denominator Lewis integral. To the best of our knowledge, the distorted-wave results for the differential and total cross sections for such reactions are reported for the first time in the literature.

Physical Review A, 2005

The scattering amplitude for positron-hydrogen collisions has been conveniently derived within th... more The scattering amplitude for positron-hydrogen collisions has been conveniently derived within the framework of distorted-wave theory by approximating the distortion potential in a particular channel as the average of perturbation of that particular channel over the bound states. A real advantage of this method is that a few straightforward calculations yield the expression of scattering amplitude as a function of partial wave. The method has been successfully applied to study 1s-2s excitation of hydrogen atom by positron impact and Ps ͑ns͒ ͑n = 1,2,3͒ formation in positron-hydrogen collisions in the intermediate and high energy range. Further to bring the scattering amplitudes in tracktable forms we have formulated an effective and efficient method for evaluating general three-denominator Lewis integral. The results compare nicely with other theoretical and experimental results available in the literature.

Physical Review A, Oct 14, 2005

Research Interests  Atomic & Molecular collisions.  Atomic collisions in plasmas.  Atomic and ... more Research Interests  Atomic & Molecular collisions.  Atomic collisions in plasmas.  Atomic and Molecular structure in plasmas.  Interaction of positron and positronium with atoms.  Atoms in external electric and magnetic fields.  Mathematical physics.

Chinese Journal of Physics, Jun 1, 2021

Abstract The dynamics of positron scattering from the ground state of lithium, sodium and potassi... more Abstract The dynamics of positron scattering from the ground state of lithium, sodium and potassium atoms in hot and dense plasmas has been investigated by applying a two-state approximation that includes elastic scattering and rearrangement scattering. The wave functions and energies of the target alkali atoms have been determined quite accurately within the framework of the ’method of model potential’. An inclusive study was made on the effects of plasma screening on the differential and total cross sections for elastic scattering and positronium formation in the ground state for the incident positron energy lying within 10 eV to 500 eV. For the unscreened case, our present results agree reasonably with the results of other calculations. It was found that the cross sections suffer considerable change due to the effects of the background plasma.

Physical Review A, Oct 14, 2005

A detailed study is made of the elastic differential cross section in positron-hydrogen collision... more A detailed study is made of the elastic differential cross section in positron-hydrogen collisions using the accurate Schwinger variational results for partial waves up to l = 19 of the preceding paper ͓Ghoshal and Mandal, Phys. Rev. A, 72, 042709 ͑2005͔͒. Dramatic behavior of the differential cross section is evident in the surface plots, suggesting interference of partial-wave contributions at small and large scattering angles for the appearance of rich structure. It is found that the behavior of the critical point basically characterizes the nature of the differential cross section. Further interferences of the scattered waves for different angular momentum states produced by the interaction between the incoming positron and the target hydrogen atom determine such behavior and consequently build up the nature of the differential cross section. These findings reveal the remarkable fact that positron-hydrogen scattering almost does not occur in the direction around 87.3°at an incident energy of about 3.4 eV, corresponding to incident positron momentum of 0.5 atomic units.

Physical Review A, Sep 14, 2005

The scattering amplitude for positron-hydrogen collisions has been conveniently derived within th... more The scattering amplitude for positron-hydrogen collisions has been conveniently derived within the framework of distorted-wave theory by approximating the distortion potential in a particular channel as the average of perturbation of that particular channel over the bound states. A real advantage of this method is that a few straightforward calculations yield the expression of scattering amplitude as a function of partial wave. The method has been successfully applied to study 1s-2s excitation of hydrogen atom by positron impact and Ps ͑ns͒ ͑n = 1,2,3͒ formation in positron-hydrogen collisions in the intermediate and high energy range. Further to bring the scattering amplitudes in tracktable forms we have formulated an effective and efficient method for evaluating general three-denominator Lewis integral. The results compare nicely with other theoretical and experimental results available in the literature.

Physica Scripta, 2003

Two types of correlated wavefunctions are considered for the ground state of helium iso-electroni... more Two types of correlated wavefunctions are considered for the ground state of helium iso-electronic systems in the forms in a.u.: (a) C ¼ P c i r li 1 r mi 2 r ni 12 exp½ÀðAr 1 þ Br 2 þ m i r 12 Þ þ ð1 *) 2Þ, and (b) C ¼ P c i r li 1 r mi 2 r ni 12 exp½ÀAðr 1 þ r 2 Þ=ða þ br 12 Þ m0 þ ð1 *) 2Þ; where l þ m þ n oðintegerÞ, and m 0 ¼ 1 2 ; 3 2 ;... Several wavefunctions, starting from the smallest number of terms, are reported in this work.The sets of the exponential correlation parameter m i and the inverse correlation parameter b are optimized by the Monte-Carlo method along with the other nonlinear variation parameters A; B to obtain quite accurate eigenenergies. At most a total number of 14 terms of type (a) and 25 terms of type (b) are required to obtain results in close agreement with the non-relativistic limits for all the systems. These values are compared with the results available in the literature.

Journal of Physics B, Mar 16, 2017

European Physical Journal D, Sep 1, 2017

Effects of nonideality of classical plasma on the reaction: p + H(1s) → H(nlm) + p has been inves... more Effects of nonideality of classical plasma on the reaction: p + H(1s) → H(nlm) + p has been investigated by carrying out fully quantum mechanical calculations within the framework of a first-order distorted wave method. Scattering amplitude is calculated conveniently by employing a simple, variationally determined wave function of hydrogen atom embedded in nonideal classical plasma. A detailed study is made on the changes in electron transfer cross sections due to the nonideality of plasma varying from 0 to 4 and the incident proton energy lying between 10 and 500 keV. It has been found that nonideality of plasma causes substantial change in capture cross section.

Modern Physics Letters B, Jun 30, 2023

In this paper, the effects of plasmas on the S-wave resonance states in the positron-potassium sy... more In this paper, the effects of plasmas on the S-wave resonance states in the positron-potassium system are investigated. Two different plasma conditions are considered, namely weakly coupled classical plasma (WCCP) and dense quantum plasma (DQP). The effective interaction potential in WCCP and DQP has been described by the Debye–Hückel model (static screened Coulomb potential) and a modified version of Debye–Hückel model (exponential cosine screened potential). Resonance parameters are determined by calculating the energy-density within the framework of the stabilization method. For the plasma-free case, three states, lying below the Ps[Formula: see text] threshold, are identified. The energy and the width agree well with the existing results in the literature. A detailed study is carried out to explore the changes emerging in the resonance parameters due to screening effects of WCCP and DQP. It is found that the energies of the three states are gradually pushed toward the Ps[Formula: see text] threshold due to the increasing plasma screening strength, whereas widths of the states vary differently.

Chinese Journal of Physics, Dec 1, 2010

Elastic scattering of low-energy electrons from the ground state of hydrogen atoms in dense quant... more Elastic scattering of low-energy electrons from the ground state of hydrogen atoms in dense quantum plasma environments has been studied using an effective range theory. We use the exponential cosine-screened Coulomb potential (ECSCP) to represent the plasma screening effect in a dense quantum plasma. Highly correlated Hylleraas-type wave functions for H(superscript -) are used to determine the effective range of the ion states. The results for S-wave singlet phase shifts in dense quantum plasmas are reported for the incident electron energy in the range for which only the elastic channel is open. Furthermore, we have compared the plasma screening effect of a dense quantum plasma with that of a weakly-coupled plasma, for which the plasma screening effect has been represented by the Debye model. Our results for the unscreened case agree nicely with some of the most accurate results available in the literature.

Chinese Journal of Physics, Oct 1, 2021

Abstract Effects of the hot and dense plasma on the doubly excited states (DES) of the four-elect... more Abstract Effects of the hot and dense plasma on the doubly excited states (DES) of the four-electron beryllium-like ions (BLI) with Z varying from 4 to 10 have been investigated by applying the stabilization method. The Debye–Huckel model has been used to describe the effective potential in the plasma. The four-electron ions are treated as an effective three-body problem by means of the method of model potential. One, four and five DESs lying above the 1s 2 2p threshold are found to exist in the ions having Z = 4 , Z = 5 and Z = 6 − 10 respectively. For the plasma-free case our results for the energy and width of the DESs are in agreement with the available results in the literature. A detailed study is made on the changes of energy and width of the DESs of the ions with varying plasma screening strength. Particular emphasis is given to explore the effects of the plasma on the whole sequence of ions.

Journal of Physics B, May 19, 2010

Bulletin of the American Physical Society, May 21, 2009

−λr cos(λr) (in a.u.), where r denotes the inter-particle distance. Within the framework of Ritz'... more −λr cos(λr) (in a.u.), where r denotes the inter-particle distance. Within the framework of Ritz's variational principle and making use of a highly correlated wave function, we have determined the ground state energies and wave functions of the helium atom for different values of the screening parameterλ. Furthermore, we have shown that the ground state energy of helium for a particular value of λ does converge with increasing number of terms in the wave function. In addition, using the stabilization method, we have investigated the doubly excited 2s 2 1 S e resonance state in helium with ECSCP. Resonance energy and width for various λ values are calculated. Our present work will play a useful role in the investigations of atomic structures in quantum plasmas [1]. [1]. P.K. Shukla and B.

Physical Review E, Jan 20, 2010