## Ultracold chemistry with alkali-metal–rare-earth molecules

## Abstract

Here, a first principles study of the dynamics of ^{6}Li( ^{2}S) + ^{6}Li ^{174}Yb( ^{2}Σ ^{+}) → ^{6}Li _{2}( ^{1}Σ ^{+}) + ^{174}Yb( ^{1}S) reaction is presented at cold and ultracold temperatures. The computations involve determination and analytic fitting of a three-dimensional potential energy surface for the Li _{2} Yb system and quantum dynamics calculations of varying complexities, ranging from exact quantum dynamics within the close-coupling scheme, to statistical quantum treatment, and universal models. It is demonstrated that the two simplified methods yield zero-temperature limiting reaction rate coefficients in reasonable agreement with the full close-coupling calculations. The effect of the three-body term in the interaction potential is explored by comparing quantum dynamics results from a pairwise potential that neglects the three-body term to that derived from the full interaction potential. Inclusion of the three-body term in the close-coupling calculations was found to reduce the limiting rate coefficients by a factor of two. The reaction exoergicity populates vibrational levels as high as v = 19 of the ^{6}Li _{2} molecule in the limit of zero collision energy. Product vibrational distributions from the close-coupling calculations reveal sensitivity to inclusion of three-body forces in the interaction potential. In conclusion, the results indicate thatmore »

- Authors:

- Temple University, Philadelphia, PA (United States)
- Univ. of Nevada, Las Vegas, NV (United States)
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Instituto de Física Fundamental, IFF-CSIC, Madrid (Spain)

- Publication Date:

- Research Org.:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

- Sponsoring Org.:
- USDOE National Nuclear Security Administration (NNSA); USDOE Laboratory Directed Research and Development (LDRD) Program

- OSTI Identifier:
- 1471323

- Alternate Identifier(s):
- OSTI ID: 1181234

- Report Number(s):
- LA-UR-14-28770

Journal ID: ISSN 1050-2947; PLRAAN

- Grant/Contract Number:
- AC52-06NA25396; 20140309ER

- Resource Type:
- Accepted Manuscript

- Journal Name:
- Physical Review. A

- Additional Journal Information:
- Journal Volume: 91; Journal Issue: 1; Journal ID: ISSN 1050-2947

- Publisher:
- American Physical Society (APS)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; ultracold; cold; molecules; scattering; chemical reaction

### Citation Formats

```
Makrides, C., Hazra, J., Pradhan, G. B., Petrov, A., Kendrick, Brian Kent, González-Lezana, T., Balakrishnan, N., and Kotochigova, S. Ultracold chemistry with alkali-metal–rare-earth molecules. United States: N. p., 2015.
Web. doi:10.1103/PhysRevA.91.012708.
```

```
Makrides, C., Hazra, J., Pradhan, G. B., Petrov, A., Kendrick, Brian Kent, González-Lezana, T., Balakrishnan, N., & Kotochigova, S. Ultracold chemistry with alkali-metal–rare-earth molecules. United States. doi:10.1103/PhysRevA.91.012708.
```

```
Makrides, C., Hazra, J., Pradhan, G. B., Petrov, A., Kendrick, Brian Kent, González-Lezana, T., Balakrishnan, N., and Kotochigova, S. Tue .
"Ultracold chemistry with alkali-metal–rare-earth molecules". United States. doi:10.1103/PhysRevA.91.012708. https://www.osti.gov/servlets/purl/1471323.
```

```
@article{osti_1471323,
```

title = {Ultracold chemistry with alkali-metal–rare-earth molecules},

author = {Makrides, C. and Hazra, J. and Pradhan, G. B. and Petrov, A. and Kendrick, Brian Kent and González-Lezana, T. and Balakrishnan, N. and Kotochigova, S.},

abstractNote = {Here, a first principles study of the dynamics of 6Li(2S) + 6Li174Yb(2Σ+) → 6Li2(1Σ+) + 174Yb(1S) reaction is presented at cold and ultracold temperatures. The computations involve determination and analytic fitting of a three-dimensional potential energy surface for the Li2 Yb system and quantum dynamics calculations of varying complexities, ranging from exact quantum dynamics within the close-coupling scheme, to statistical quantum treatment, and universal models. It is demonstrated that the two simplified methods yield zero-temperature limiting reaction rate coefficients in reasonable agreement with the full close-coupling calculations. The effect of the three-body term in the interaction potential is explored by comparing quantum dynamics results from a pairwise potential that neglects the three-body term to that derived from the full interaction potential. Inclusion of the three-body term in the close-coupling calculations was found to reduce the limiting rate coefficients by a factor of two. The reaction exoergicity populates vibrational levels as high as v = 19 of the 6Li2 molecule in the limit of zero collision energy. Product vibrational distributions from the close-coupling calculations reveal sensitivity to inclusion of three-body forces in the interaction potential. In conclusion, the results indicate that a simplified model based on the long-range potential is able to yield reliable values of the total reaction rate coefficient in the ultracold limit but a more rigorous approach based on statistical quantum or quantum close-coupling methods is desirable when product rovibrational distribution is required.},

doi = {10.1103/PhysRevA.91.012708},

journal = {Physical Review. A},

number = 1,

volume = 91,

place = {United States},

year = {2015},

month = {1}

}

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