# Oleg Zatsarinny (1953–2021): Memories by His Colleagues

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## Abstract

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## 1. Introduction

## 2. Individual Memories

#### 2.1. Alexei N. Grum-Grzhimailo (Lomonosov Moscow State University, Moscow, Russia)

#### 2.2. Klaus Bartschat (Drake University, Des Moines, Iowa, USA)

#### 2.3. Charlotte Froese Fischer (University of British Columbia, Vancouver, Canada)

I agreed to referee a paper where collision strengths for specific transitions are reported. They refer to a Wang, Bartschat, Zatsarinny (2018) paper using BSR which I suspect included Breit-Pauli. Can I have a copy of your paper?

Did you vote today?! How are things going?

That makes two of us—I was also assigned as referee to this paper. Attached is a copy of our paper.

The present paper is a step further—it considers fine-structure transitions. However, the accuracy of target states is still far from accurate, to such extent that to bother about small Breit corrections makes no sense, I think. And it is a problem of modern atomic-structure software—nobody yet gets accurate description of transition elements with open 3d shells, especially for scattering calculations where configuration expansions should be rather restricted.

No, I did not vote, it is far from my life, I am still Russian guy, and never feel myself as American. But it will be interesting to follow all this performance ...

Due to some health I don’t work much these days.

#### 2.4. Athanasios Petridis (Drake University, Des Moines, Iowa, USA)

#### 2.5. Adina Kilpatrick (Drake University, Des Moines, Iowa, USA)

#### 2.6. Kathryn R. Hamilton (Drake University, Des Moines, Iowa, USA)

#### 2.7. Former Students David Atri-Schuller, Doug Drake, Molly McCord, Thomas Pauly, and Will Thomas (Drake University, Des Moines, Iowa, USA)

#### 2.7.1. David Atri-Schuller, Graduate Student at Stanford University, Palo Alto, California, USA

#### 2.7.2. Doug Drake, Graduate Student at The University of Missouri-Kansas City, Kansas City, Missouri, USA

#### 2.7.3. Molly McCord, Graduate Student at The University of Wisconsin-Madison, Madison, Wisconsin, USA

#### 2.7.4. Thomas Pauly, Software Engineer at Forsman Farms, Howard Lake, Minnesota, USA

#### 2.7.5. Will Thomas, Graduate Student at The University of Wisconsin-Madison, Madison, Wisconsin, USA

#### 2.8. Luis Fernandez-Menchero (Queen’s University of Belfast, Northern Ireland)

#### 2.9. Nicolas Douguet (Kennesaw State University, Atlanta, Georgia, USA) and Samantha Fonseca (Rollins College, Orlando Florida, USA)

#### 2.10. Hartmut Hotop (University of Kaiserslautern, Germany) and Michael Allan (University of Fribourg, Switzerland)

#### 2.11. Alexander Dorn (Max-Planck Institute for Nuclear Physics, Heidelberg, Germany)

#### 2.12. Barry I. Schneider and Collin (Xiaoxu) Guan (National Institute for Science and Technology, Gaithersburg, USA)

#### 2.13. Yuri Ralchenko (National Institute for Science and Technology, Gaithersburg, Maryland, USA)

#### 2.14. Yang Wang (Harbin Institute of Technology, Harbin, People’s Republic of China)

#### 2.15. Kedong Wang (Henan Normal University, Xinxiang, People’s Republic of China)

#### 2.16. Zhangjin Chen (Shantou University, Guangdong, People’s Republic of China)

#### 2.17. Igor Bray, Dmitry Fursa, and Alisher Kadyrov (Curtin University, Perth, Australia)

#### 2.18. Anatoli Kheifets (Australian National University, Canberra, Australia)

#### 2.19. Michael J. Brunger (Flinders University, Adelaide, Australia)

#### 2.20. Swaraj Tayal (Clark Atlanta University, Atlanta, Georgia, USA)

#### 2.21. Leanne Pitchford (University of Toulouse, France, on behalf of the LXCat Team)

#### 2.22. Luis L. Alves (University of Lisbon, Lisbon, Portugal)

Dear Luis,Well, believe it or not, but we actually did this calculation already and published the results recently. I am attaching the PDF file of our paper. I’ll also CC Oleg Zatsarinny on this reply. He can probably send you the numerical results, so you don’t have to take them from the graph.Best wishes,Klaus

Dear Luis,Attached is archive of our last results for the e-N problem. It includes also the momentum-transfer cross sections you are interested in (mt-files, look in “read_me” for explanations)Hope this will help,Oleg Zatsarinny

#### 2.23. Anna Dzarasova (London, United Kingdom, on behalf of the Quantemol Team)

#### 2.24. Paul Barklem, Anish Amarsi, and Jon Grumer (Uppsala University, Uppsala, Sweden)

## 3. Conclusions

## Author Contributions

## Funding

## Conflicts of Interest

## References

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**Figure 1.**Oleg Zatsarinny. Freiburg, 30 November 1994. Photo from private collection of A.N. Grum-Grzhimailo.

**Figure 2.**Angle-integrated cross section for production of neon atoms in the metastable states $3\mathrm{s}{[3/2]}_{2}$ and $3{\mathrm{s}}^{\prime}{[1/2]}_{0}$. The experimental data of Buckman et al. [10] (thick dots) were renormalized to provide a good visual fit to the theory at energies just above the excitation threshold. The solid line includes the cascade contributions from all the states included in the model, while the thin dotted line (starting around 18.4 eV) represents the results without cascades. Figure reproduced from Ref. [11].

**Figure 3.**A group outing in 2017. From left to right with their countries of origin in parentheses: Samantha Fonseca (Brazil), Nicolas Douguet (France), Tatyana Zatsarinny (Ukraine), Raquel Pinto $\stackrel{\xb4}{\mathrm{A}}$lvarez (Spain), Kedong Wang (China), Luis Fern$\stackrel{\xb4}{\mathrm{a}}$ndez-Menchero (Spain), Teresa Bartschat (Canada), and Oleg Zatsarinny (Ukraine). Photo from private collection of Klaus Bartschat.

**Figure 4.**Charlotte and Oleg working on the DBSR_HF project (May 2015) at Oleg’s home in West Des Moines. Photo from private collection of Charlotte Froese Fischer.

**Figure 6.**Excitation cross section (in units of ${10}^{-2}\phantom{\rule{0.166667em}{0ex}}{a}_{0}^{2}$; ${a}_{0}$ is the Bohr radius) for the production of metastable Ne${\left(2{\mathrm{p}}^{5}3\mathrm{s}\right)}^{3}{\mathrm{P}}_{2,0}$ atoms in the energy range 16.5 to 19.0 eV. Open circles: measurement [17]. Full curve: B-spline R-matrix theory [including cascade contributions and assuming identical detection efficiencies for Ne${\left(2{\mathrm{p}}^{5}3\mathrm{s}\right)}^{3}{\mathrm{P}}_{2}$ and Ne${\left(2{\mathrm{p}}^{5}3\mathrm{s}\right)}^{3}{\mathrm{P}}_{0}$ atoms]. Broken curve: theoretical excitation function for the production of Ne${\left(2{\mathrm{p}}^{5}3\mathrm{s}\right)}^{3}{\mathrm{P}}_{0}$, including cascade contributions. Inset: enlarged view of the data over the energy region 18.48−18.58 eV, revealing a narrow Feshbach resonance (see text).

**Figure 7.**Absolute cross sections for excitation of the Ne$\left(2{\mathrm{p}}^{5}3\mathrm{s}\right)$ states at $\theta ={180}^{\circ}$. The experimental data are in the left and the theoretical predictions in the right panel. Thresholds for the $2{\mathrm{p}}^{5}3\mathrm{s}$, $2{\mathrm{p}}^{5}3\mathrm{p}$, and $2{\mathrm{p}}^{5}4\mathrm{s}$ excitations are indicated below the top spectra. From [18].

**Figure 8.**Fully differential cross sections for electron-impact ionization of argon covering almost the full $4\pi $ solid angle for electron emission [23]. The projectile (${\mathbf{p}}_{0},{E}_{0}=66\phantom{\rule{3.33333pt}{0ex}}$eV) is coming in from below and scattered to the left ${\mathbf{p}}_{1}$. The FDCS is plotted as a function of the emission angle of the electron ejected from the Ar$\left(3{\mathrm{p}}^{6}\right)$ subshell with kinetic energy ${E}_{2}=3\phantom{\rule{3.33333pt}{0ex}}$eV. $\mathbf{q}$ is the momentum transfer vector. (

**a**) Experiment using a Reaction Microscope. (

**b**) BSR theory.

**Figure 9.**Generalized cross section for two-photon ionization of Ar ${\left(3{\mathrm{p}}^{6}\right)}^{1}\mathrm{S}$ as a function of photon energy [25]. A 30-cycle laser pulse with a peak intensity of ${10}^{12}\phantom{\rule{0.166667em}{0ex}}$ W/cm${}^{2}$ was used in the calculations. The filled circles represent the results obtained by using the total ionization yield, while the open circles show those generated by summing up the partial ionization yields from the individual channels. The Floquet results are from McKenna and van der Hart [27].

**Figure 10.**Photo of a get-together before I left Des Moines in 2013. Photo from the private collection of Yang Wang.

**Figure 11.**Kedong Wang (left), Tatyana Zatsarinny (middle) and Oleg Zatsarinny (right on the Great Wall in 2017. Photo from the private collection of Kedong Wang.

**Figure 12.**Differential cross section for electron impact excitation of Ar${}^{+}$ from the ground state $3{\mathrm{s}}^{2}3{\mathrm{p}}^{5}$ to the excited states with configurations $3{\mathrm{s}}^{2}3{\mathrm{p}}^{4}3\mathrm{d}$ (

**a**), $3{\mathrm{s}}^{2}3{\mathrm{p}}^{4}4\mathrm{s}$ (

**b**), and $3{\mathrm{s}}^{2}3{\mathrm{p}}^{4}4\mathrm{p}$ (

**c**) at incident energies of 20, 30, 40, and 50 eV, respectively. In panel (

**d**), the total cross sections for electron impact excitation of Ar${}^{+}$ to the excited states with configurations $3\mathrm{s}3{\mathrm{p}}^{6}$, $3{\mathrm{s}}^{2}3{\mathrm{p}}^{4}3\mathrm{d}$, $3{\mathrm{s}}^{2}3{\mathrm{p}}^{4}4\mathrm{s}$, and $3{\mathrm{s}}^{2}3{\mathrm{p}}^{4}4\mathrm{p}$ and electron-impact ionization of Ar${}^{+}$ from the ground state are also displayed. For excitation, all results were obtained with the BSR code. For ionization, the total cross sections were calculated by using the semiempirical formula of Lotz [44]. From Chen et al. [45].

**Figure 13.**Electron-impact excitation cross sections for the dipole-allowed $({2}^{1}\mathrm{S}\to {2}^{1}\mathrm{P})$ and dipole-forbidden $({3}^{3}\mathrm{P}\to {4}^{3}\mathrm{P})$ transitions in neutral beryllium. Dashed lines with squares, dotted lines with triangles and solid lines represent BSR, CCC and fitted results, respectively [28].

**Figure 14.**Taking a break from exploring the Australian hinterland. Photo from private collection of Anatoli Kheifets.

**Figure 15.**Oleg in his office at Clark Atlanta University 20 years ago. Photo from private collection of Swaraj Tayal.

**Table 1.**Dirac-Slater integrals for hydrogen ($Z=1$) to double-precision accuracy, as derived by Oleg for a point nucleus.

Integral | Value |
---|---|

${R}_{0}(1\mathrm{s},1\mathrm{s};1\mathrm{s},1\mathrm{s})$ | 0.62501225565917420 |

${R}_{0}(1\mathrm{s},2\mathrm{s};1\mathrm{s},2\mathrm{s})$ | 0.20988178946000520 |

${R}_{0}(1\mathrm{s},2\mathrm{s};2\mathrm{s},1\mathrm{s})$ | 0.02194902302127903 |

${R}_{0}(1\mathrm{s},2\mathrm{p};1\mathrm{s},2\mathrm{p})$ | 0.24280005588417670 |

${R}_{0}(1\mathrm{s},2\mathrm{p}-;1\mathrm{s},2\mathrm{p}-)$ | 0.24280528746571910 |

${R}_{1}(1\mathrm{s},2\mathrm{p};2\mathrm{p},1\mathrm{s})$ | 0.05121117625724148 |

${R}_{0}(1\mathrm{s},3\mathrm{d};1\mathrm{s},3\mathrm{d})$ | 0.11102328042993430 |

${R}_{0}(1\mathrm{s},3\mathrm{d}-;1\mathrm{s},3\mathrm{d}-)$ | 0.22128364373246080 |

${R}_{0}(2\mathrm{p},3\mathrm{d};2\mathrm{p},3\mathrm{d})$ | 0.18528097106484610 |

${R}_{0}(3\mathrm{d},3\mathrm{d};3\mathrm{d},3\mathrm{d})$ | 0.08604622596773348 |

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Bartschat, K.; Fischer, C.F.; Grum-Grzhimailo, A.N.
Oleg Zatsarinny (1953–2021): Memories by His Colleagues. *Atoms* **2021**, *9*, 109.
https://doi.org/10.3390/atoms9040109

**AMA Style**

Bartschat K, Fischer CF, Grum-Grzhimailo AN.
Oleg Zatsarinny (1953–2021): Memories by His Colleagues. *Atoms*. 2021; 9(4):109.
https://doi.org/10.3390/atoms9040109

**Chicago/Turabian Style**

Bartschat, Klaus, Charlotte Froese Fischer, and Alexei N. Grum-Grzhimailo.
2021. "Oleg Zatsarinny (1953–2021): Memories by His Colleagues" *Atoms* 9, no. 4: 109.
https://doi.org/10.3390/atoms9040109