# R.K. JanevMacedonian Academy of Sciences and Arts | MANU

R.K. Janev

Member of MASA

## About

397

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Introduction

Additional affiliations

January 2000 - present

January 2000 - present

**Macedonian Academi of Sciences and Arts**

Position

- Member of MASA

## Publications

Publications (397)

Total and subshell-selective charge exchange cross sections and the corresponding reaction rate coefficients for Neq+-H (q=6–10) collision systems are calculated by utilizing the two-center atomic orbital close-coupling (TC-AOCC) method at impact energy between 0.1 keV/u and 500 keV/u. Good agreements with the experimental and other theoretical res...

The free-free Gaunt factors as functions of the initial electron energy εi of hydrogen-like ions are investigated, for a typical photon absorption energy of ω= 10 Ry in strongly coupled quantum plasmas, where the screened Coulomb interactions are modeled as the cosine-Debye–Hückel potentials. The free-free Gaunt factors in the strongly coupled quan...

Electron-impact cross sections for the v → v ′ transitions between the vibrational levels of X¹Σ⁺ and A¹Σ⁺ electronic states of the LiH molecule, are calculated from threshold to 1000 eV by using the threshold-modified Massey–Mott approximation. The rate coefficients for the same transitions are also calculated in the range 0.1–1000 eV. Scaling rel...

Elastic scattering of electrons and positrons on a Friedel potential is studied in quantum plasmas with electron densities in the range of 10²²–10²⁷ cm⁻³ and particle collision energies in the range of 10⁻⁶–10² a.u. by using the partial wave decomposition of the scattering wavefunction. The total and partial-wave cross sections for electron and pos...

A contour deformation method (CDM) in the complex momentum plane has been successfully extended and implemented to probe resonances in atomic and molecular systems. Specifically, solution of the Schrödinger equation is performed in momentum space with momentum deformed on a contour in the complex plane. The bound, resonant, and complex continuum st...

To well predict the emitted spectrum of ionized plasmas, the modern spectral synthesis codes need thermally averaged free-free Gaunt factors in a wide plasma temperature and density range. However, the plasma screening effects on the Gaunt factors have rarely been studied and taken into account in the emission calculations. In this work, we compreh...

Aims . Electron capture in collisions of highly charged O ⁶⁺ ions with ground-state hydrogen atoms is a very important process in solar wind X-ray studies.
Methods . In the present study, the full quantum-mechanical molecular-orbital close-coupling method is employed to study electron capture reactions in collisions of O ⁶⁺ ion with ground-state at...

The full quantum molecular orbital close-coupling (QMOCC) method and optical potential method have been employed to study the nonradiative charge transfer and radiative decay processes for Li ⁻ colliding with H atoms. The cross sections of these processes are calculated rigorously in the energy range of 0.1–1.2 eV. It is found that rich and signifi...

The effect of Coulomb interaction screening on nonrelativistic free-free absorption is investigated by integrating the numerical continuum wave functions. The screened potential is taken to be in Debye-Hückel (Yukawa) form with a screening length D. It is found that the values of the free-free Gaunt factors for different Debye screening lengths D f...

The effect of Coulomb interaction screening on non-relativistic free-free absorption is investigated by integrating the numerical continuum wave functions. The screened potential is taken to be in Debye-H\H{u}ckel (Yukawa) form with a screening length D. It is found that the values of the free-free Gaunt factors for different Debye screening length...

The spectral line intensities and line shifts of Lyman and Balmer series for transitions up to n = 5 of hydrogen-like ion are studied in plasmas with densities and temperatures in the ranges ne ∼ 10¹⁸–10²¹ cm⁻³, Te = 0.3–1.2 eV respectively. The screened potential used to describe the interaction between charged particles includes the electron exch...

The photoionization process of the C⁵⁺ ion in warm, dense plasmas is studied using the relativistic approximation. Cross section calculations are performed for plasma density and temperature ranges of ne ∼ 10²³–10²⁶ cm⁻³ and Te = 150–300 eV, respectively. The used static screened potential includes the effects of plasma degeneracy, finite-temperatu...

Electron capture and excitation processes in H⁺-H collisions imbedded in warm dense quantum plasmas are studied by the two-center atomic orbital close-coupling (TC-AOCC) method in the energy range 1–200 keV. The screened potential which is used to describe the interaction between charged particles incorporates the quantum electron degeneracy, excha...

Low-energy electron elastic scattering and impact ionization with hydrogenlike helium in Debye plasmas have been investigated by employing the exterior complex scaling method. The interactions between charged particles in the plasmas have been represented by Debye-Hückel potentials. The 1s−1s elastic collision strengths below the n=2 excitation thr...

The photoionization of hydrogen-like ions in n≤3 bound states, embedded in cold, dense quantum plasmas, is investigated in detail. The electron energies and wave functions for the bound and continuum states are determined by numerically solving the scaled Schrödinger equation by the fourth-order symplectic integration scheme. The monotonic behavior...

We report cross-sections and rate coefficients for excited states colliding with electrons, heavy particles and walls useful for the description of H 2 /He plasma kinetics under different conditions. In particular, the role of the rotational states in resonant vibrational excitations of the H 2 molecule by electron impact and the calculation of the...

The oscillator strengths and radiative transition probabilities for the Lyman and Balmer series for transitions up to n = 5 of a hydrogen-like ion embedded in a finite-temperature quantum plasma are calculated in a wide range of plasma densities and temperatures for the first time. The plasma screened Coulomb interaction includes the quantum electr...

Aims. The radiative charge transfer and association processes in Li⁻ + H collisions are studied in the 10⁻¹⁰-10 eV center-of-mass energy range. Methods. we carried out total and ν-resolved state-selective cross sections have been carried out by using the fully quantum, optical potential, and semiclassical methods. Results. In the energy region belo...

A theoretical study of resonant vibrational excitation, dissociative recombination and
dissociative excitation processes of the beryllium monohydride cation, BeH+, induced by
electron impact, is reported. Full sets of ro-vibrationally-resolved cross sections and of the
corresponding Maxwellian rate coefficients are presented for the three processes...

Low energy electron-impact ionization of hydrogen atom in Debye plasmas has been investigated by employing the exterior complex scaling method. The interactions between the charged particles in the plasma have been represented by Debye-Hückel potentials. Triple differential cross sections (TDCS) in the coplanar equal-energy-sharing geometry at an i...

Electron capture and excitation processes in proton–hydrogen atom collisions taking place in dense quantum plasmas are studied by employing the two-centre atomic orbital close-coupling (TC-AOCC) method. The Debye–Hückel cosine (DHC) potential is used to describe the plasma screening effects on the Coulomb interaction between charged particles. The...

Hot, dense plasmas exhibit screened Coulomb interactions, resulting from the collective effects of correlated many-particle interactions. In the lowest particle correlation order (pair-wise correlations), the interaction between charged plasma particles reduces to the Debye-H\"uckel (Yukawa-type) potential, characterized by the Debye screening leng...

The electron capture processes in the C5+(1s)+H(1s) collision system are investigated by the quantum-mechanical molecular orbital close-coupling (QMOCC) method in the energy range of 10−5–10 keV u−1. Accurate molecular structure calculations are performed by the ab initio multireference single- and double-excitation configuration interaction method...

The effects of screened Coulomb interaction on the alignment of H(2p) state produced in collisions of hydrogen atoms with protons and antiprotons are investigated in the energy range 1–200 keV by using the two-center atomic orbital close-coupling (TC-AOCC) method. It is shown that the decrease of the binding energy of hydrogen nl-states and the red...

The properties of bound-bound transitions in hydrogen-like ions in dense quantum plasmas, characterized by a cosine-Debye-Hückel interaction between charged particles, are studied in detail. The transition frequencies, oscillator strengths, and radiative transition probabilities of Lyman and Balmer series are calculated for a wide range of screenin...

The modeling of atmospheric gas, interacting with the space vehicles in re-entry conditions in planetary exploration missions, requires a large set of scattering data for all those elementary processes occurring in the system. A fundamental aspect of re-entry problems is represented by the strong non-equilibrium conditions met in the atmospheric pl...

The electron capture and excitation processes in collisions of He+-Li are investigated theoretically by using the two-center atomic orbital close-coupling method in the energy range 0.1–100 keV u−1. The interaction of active electrons with the projectile ion is represented by a model potential different for the singlet and triplet systems of He sta...

The charge exchange and collisional detachment processes in H- + Li and Li- + H collisions have been studied by using the quantal molecular orbital close-coupling (QMOCC) method in the energy ranges of about 0.12-1000 eV u(-1) and 0.1 meV-1000 eV, respectively, and the inelastic collision cross sections and rate coefficients have been computed and...

Electron-impact cross sections for the dissociation process of vibrationally excited He+2 molecular ion, as a function of the incident electron energy are calculated for the dissociative transition X 2σ+u → A 2σ +g by using the R-matrix method in the adiabatic-nuclei approximation. The potential energy curves for the involved electronic states and...

The excitation of a ground state Li atom to its 1s2nd (n = 3–5) excited states in a collision with He2+ is investigated using the two-center atomic orbital close-coupling method. The Li(nd → 2p) emission cross-sections are calculated in the collision energy range of 1–150 keV u−1 and compared with the available experimental cross-sections and other...

The charge transfer process in C5+-H collisions has been theoretically studied using the two-center atomic orbital close-coupling method in the energy interval from 0.1 to 300 keV u−1. The interaction of active electron with the projectile ion is represented by model potentials different for the singlet and triplet systems of C4+(1snl) states. The...

The linear polarization degree of Balmer alpha radiation resulting from H++H (1s) collisions in a hot, dense weakly coupled plasma is studied in the energy range 1 - 140 keV/u by adopting the Debye-Hückel potential to represent the screened interaction between charged plasma particles. Due to the energy splitting of nl hydrogen states in the short...

The collision processes of proton with H(1s) atoms, which is embedded in strong transverse magnetic fields perpendicular to the initial velocity of the projectile, are studied with the classical trajectory Monte Carlo method in the energy range 25 keV/u–2000 keV/u and B ∼ 104 T. It is found that the charge exchange cross section is decreased while...

The two-center atomic orbital close-coupling method is employed to study electron capture and excitation processes in proton collisions with the metastable Be(1s2s2p P) atom. The interaction of the active electron with the Be ion core is represented by a model potential reproducing accurately (to within 3.5%) the energies of triplet excited states...

The electron capture processes in Li2+ + H collisions have been investigated by using the quantum-mechanical molecular-orbital close-coupling method and the two-center atomic-orbital close-coupling method in the energy ranges of 10(-8) -10 keV/u and 0.1-300 keV/u, respectively. The capture to singlet and triplet systems of states of Li+(1s, nl(2S+1...

The charge transfer reactions in collisions of Beq+(q=2-3) and Bq+(q=3-4) ions and atomic hydrogen are investigated by using the quantal molecular orbital close-coupling (QMOCC) and the two-center atomic-orbital close-coupling (TC-AOCC) methods. Total and sub-shells state-selective cross sections are calculated for low and intermediate energy regio...

The two-center atomic orbital close-coupling method is employed to study electron capture and excitation reactions in collisions of Liq+ (q = 1-3) ions with ground state atomic hydrogen in the ion energy range from 0.1 keV/u to 300 keV/u, where u is the atomic mass unit. The interaction of the active electron with the projectile ions (Li+, Li2+) is...

The collision-induced dissociation (CID), electron capture (EC), and dissociative capture (DC) processes in ${{\mathrm{H}}_{2}}^{+} + \mathrm{He}$ collision are investigated by the quantum-mechanical molecular-orbital close-coupling method in the energy range of 0.02\char21{}10 keV/u. The studies are based on the ab initio calculation of the molecu...

The relativistic effects in the photoionization of hydrogen-like ion with screened Coulomb interaction of Yukawa type are studied for a broad range of screening lengths and photoelectron energies. The bound and continuum wave functions have been determined by solving the Dirac equation. The study is focused on the relativistic effects manifested in...

The quantum-mechanical molecular orbital close-coupling (QMOCC) method is employed to calculate the collision-induced dissociation (CID), electron capture (EC) and dissociative capture (DC) processes in H2++He collision.

The x-ray spectra resulting from single-electron capture in charge-exchange collisions of Ne10+ with He and Ne atoms are investigated for the projectile energy of 4.54 keV/u using the two-center atomic-orbital close-coupling method. The calculated spectra of the Ne9+ ion produced in Ne10+ + He and Ne10+ + Ne electron-capture collisions have, genera...

Electron-impact theoretical cross sections and rate coefficients for
vibrational excitation of vibrationally excited H2 molecules,
occurring through the H2- resonant species
in the 2Σg+ Rydberg-excited
electronic state, are presented. The cross sections are calculated as
functions of the incident electron energy by adopting the
local-complex-potent...

Observation of BeD sputtering in several different fusion plasma devices demonstrates the need to include these molecules into predictive modeling codes. In this work, Molecular Dynamics simulations are used to obtain information about sputtered BeD molecules and the results are implemented into the plasma impurity modeling code ERO. Rates for diss...

The charge transfer processes for the Beq++H(q = 1-4)
collisions are investigated by the quantum-mechanical and semiclassical
methods in wide energy ranges. The total, n-selective, nl-selective,
singlet and triplet charge transfer cross sections are obtained and
compared with other available theoretical data. The total and
n-selective data are pres...

The low-energy erosion mechanisms of first-wall materials subject to a fusion plasma are poorly known theoretically, even though they pose a critical problem for the development of tokamak-like fusion reactors. Using molecular dynamics computer simulations and analytical theory, we have examined the fundamental mechanisms of the erosion of first-wa...

We report calculated electron impact ionization cross sections (EICSs) for beryllium (Be) and some of its hydrides from the ionization threshold to 1 keV using the Deutsch-Märk (DM) and the Binary-Encounter-Bethe (BEB) formalisms. The positions of the maxima of the DM and BEB cross sections are very close in each case while the DM cross section val...

The single- and double-electron capture processes in He2+–He collisions are investigated by the fully quantum-mechanical molecular orbital close-coupling method employing a basis containing 15 gerade and 14 ungerade molecular states. The energies and wavefunctions of He22+ molecular states included in the study are determined ab initio by the multi...

Electron-impact cross sections are calculated for the v → v' transitions occurring between the vibrational levels of the two X 2Σ+ and A 2Π electronic states of the BeH molecule. The calculations are performed with the R-matrix method for a purely vertical electronic transition for energies from threshold to 15 eV, and by using a modified version o...

The electron capture and excitation processes in collisions of H+ with excited He*(1s2s; 1,3S) atoms are investigated theoretically by using the two-centre atomic orbital close-coupling method in the energy range 2–200 keV u–1. The interaction of active electrons with the target ion is represented by a model potential different for the singlet and...

Dissociative attachment process involving a resonant Rydberg-excited
2Σ+g electronic state of the
H2- molecular ion: influence of the vibrational
excitation of the target molecule and isotopic effect.

While most of the existing models for calculation of neutral beam emission and attenuation in a fusion plasma assume a statistical distribution of population for the excited states of the beam, the observed motional Stark effect data reveal significant deviations from the statistical predictions. To address this problem, we developed a new collisio...

Plasma screening effects on the energy structure and radiative transition properties of
helium-like C4+ ions embedded in Debye plasmas are investigated by using the
multi-configuration Dirac-Hartree-Fock method incorporating the Debye-Hückel potential for
both the electron-nucleus and electron-electron interactions. Seventeen fine-structure
energy...

Dynamics of electron capture and excitation processes in collisions of H+ with the excited He(2 1,3 Lm) atom (L = S,P) has been studied by using the full quantum-mechanical molecular orbital close-coupling (QMOCC) method with ab initio determined molecular states. 38 singlet and 37 triplet molecular states of the HeH+ system, that asymptotically co...

Dissociative electron attachment cross sections (DEA) on vibrationally excited H2 molecule taking place via the 2Σg+ Rydberg-excited resonant state are studied using the local complex potential (LCP) model for resonant collisions. The cross sections are calculated for all initial vibrational levels (vi=0–14) of the neutral molecule. In contrast to...

BeH+ molecules will be an important intermediary species present in fusion plasmas with Be walls (e.g. JET, ITER), both for impurity transport and spectroscopic studies. To enable such analyses the electron-impact-induced excitations X 1Σ+(vi) → A 1Σ+(vf) and X 1Σ+(vi) → B 1Π(vf) in BeH+(vi) molecular ion, occurring between the vi and vf vibrationa...

The two-centre atomic orbital close-coupling method is employed to study the electron capture reactions in collisions of N5+ and O6+ ions with ground state atomic hydrogen in the energy range from 0.5 to 200 keV u−1. The interaction of an active electron with the projectile ion is represented by a model potential. Total and state-selective electron...

Electron-helium scattering in weakly coupled hot-dense (Debye) plasma has been investigated using the convergent close-coupling method. The Yukawa-type Debye-Hückel potential has been used to describe plasma Coulomb screening effects. Benchmark results are presented for momentum transfer cross sections, excitation, ionization, and total cross secti...

Absolute cross sections for electron impact dissociative excitation and ionization of ions of interest in thermonuclear fusion are reported for energies ranging from the respective reaction thresholds up to 2.5 keV. The animated crossed-beams method is used. Results have been measured both for heavy targets like the methane family CDn+(n = 1-4) and...

State-selective and total single-electron-capture cross sections in collisions of H+ with the excited Li*(2p) atom have been investigated by using the full quantum-mechanical molecular orbital close-coupling (QMOCC) method in the energy range 0.001–3 keV/u and by the two-center atomic orbital close-coupling (TC-AOCC) method in the energy range 0.1–...

The recently discovered multiple series of shape resonances and near-zero-energy enhancements in photoionization cross section
of hydrogen-like atomic systems with screened Coulomb (Yukawa type) interaction [Phys. Rev. A 80, 063404 (2009)] are studied in detail, in particular their evolution with the variation of the screening strength of the
poten...

The process of dissociative attachment of electrons to molecular hydrogen and its isotopes in the energy range at approximately 14 eV is investigated. The dissociative electron attachment cross sections for all six hydrogen isotopes are calculated over an extended range of electron energies using the local complex potential model with the excited R...

The effects of Coulomb interaction screening on electron-hydrogen atom 1S → 2S and 1S → 2p excitation scattering between the n = 2 and n = 3 excitation thresholds have been investigated by using the R-matrix method with pseudostates. The excitation collision strengths show dramatic changes when the interaction screening length D varies from ∞ to 9...

Polarization spectroscopy of He+(nl) ion produced in He2+-H(1s) collisions in a Debye plasma is studied by the two-center atomic orbital close-coupling (TC-AOCC) method in the energy range 1–200 keV/u. The atomic orbitals and electron binding energies of atomic states are calculated within the Debye-Hückel approximation of the screened Coulomb pote...

The present status of the atomic and molecular database required in fusion plasma edge modelling and diagnostics is briefly reviewed. Emphasis is placed on the evaluated and recommended data, and on the existing gaps and uncertainties in the database. Spectroscopic, collisional and surface data are considered.

The efficiency of neutral beam heating and current drive depends crucially on the deposition of the energy and momentum of the beam in the plasma. This deposition is determined by the atomic processes involved in the stopping (or effective ionization) of the neutral beam atoms. These processes have been studied in detail for the energy range from 1...

The experimental and theoretical data which are available for charge exchange processes involving iron ions and neutral H, H2 and He are reviewed and evaluated. A bibliography is given of available data sources, as well as of useful data compilations and review articles. Appropriate scaling laws are presented, and their accuracy estimated for these...

Differential, integral, and momentum-transfer cross sections for the rotationally elastic and inelastic scattering of electron by the BH2 radical at low collision energies (0–8 eV) are reported in a 22-state molecular R-matrix method. The excitation cross sections from the ground X 2A1 state to the first two excited states 2B1 and 4A2 are calculate...

Emission of spectral lines from the excited states of neutral beam atoms in fusion plasmas is the basis of beam emission spectroscopy and motional Stark effect diagnostics. It is well known that the measured intensities of Stark multiplet lines between the n=3 and 2 excited states of hydrogen systematically deviate from the full statistical model....

Kinetic analysis of the behaviour of hydrocarbons in fusion plasmas requires knowledge of cross sections for their most relevant collision processes. Upgrades and extensions of the commonly used HYDKIN (HYDride KINetics) online cross section database (based on compilations in 2002) and its data analysis toolbox for collisions of hydrocarbons with e...

We find that the number of vibrational states in the ground potential of a H2+ molecular ion embedded in the Debye plasma and the number of Regge oscillations in the resonant charge transfer cross section of the H+ + H collision system in the plasma are quasi-conserved when the Debye radius D is larger than 1.4a0. The elastic and resonant charge tr...

Electron capture processes in collisions of O6+ with ground state He and H2 are investigated using the two-centre atomic orbital close-coupling method. Total and state-selective one-electron capture cross sections are obtained for collision energies between 0.5 and 300 keV/u. The comparison with the available experimental state-selective capture da...

The nonradiative charge-transfer processes in Be2+(1s2)+H(1s) and B3+(1s2)+H(1s) collisions are investigated by the quantal molecular orbital close-coupling method in the energy range of 10-5eV/u–10 keV/u and by the two-center atomic-orbital close-coupling method in the energy range of 0.1–100 keV/u. The radiative charge-transfer cross sections are...

The electron capture in O6+-H collisions is studied by the two-center atomic orbital close-coupling (TC-AOCC) method when the interactions of charged particles are screened and have a Yukawa form. Atomic orbitals and eigenenergies of n ⩽ 6 states on O5+ and n ⩽ 2 states on H are calculated as a function of the interaction screening parameter and us...

The electron capture in C6+–H collisions taking place in a weakly coupled plasma is studied by the two-centre atomic orbital close-coupling method. The interaction between charged particles is represented by the Debye–Hückel potential, appropriate for weakly coupled (Debye) plasmas. The adopted two-centre expansion basis contains all the states wit...

The two-centre atomic orbital close-coupling method is employed to study charge transfer reactions in collisions of Beq+ (q = 2, 3) and Bq+ (q = 3, 4) with ground state atomic hydrogen in the energy region from 0.1 keV/u to 100 keV/u. The interaction of the active electron with the projectile ion is represented by a model potential. Total and sub-s...

The elastic scattering of protons on Be and C atoms and of Be+ and C+ ions on hydrogen atoms is investigated using the multichannel quantal molecular orbital close-coupling method. The elastic, momentum transfer and viscosity cross sections, relevant to particle transport modelling, are calculated in the energy range 10−4 eV–10 keV. The correspondi...

The effects of Coulomb interaction screening on photodetachment cross sections of hydrogen negative ions below the n =2 excitation threshold is investigated by using the R-matrix method with pseudostates. The contributions of Feshbach and shape resonances to H- photodetachment cross section are presented when screening length (D) varies from D = ∞...

Charge transfer processes in collisions of C4+ with ground-state He and H2 are investigated using the two-center atomic orbital close-coupling method. Total and state-selective single-electron capture cross sections are obtained for collision energies between 1 and 7 keV/amu, and comparison with available experimental data reveals a good agreement....