Abstract We consider the Born and inverse Born series for scalar waves with a cubic nonlinearity of Kerr type. We find a recursive formula for the operators in the Born series and prove their boundedness. This result gives conditions which guarantee convergence of the Born series, and subsequently yields conditions which guarantee convergence of the inverse Born series. We also use fixed point theory to give alternate explicit conditions for convergence of the Born series. We illustrate our results with numerical experiments.
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Comparing the collaboration networks and productivity of China-born and US-born academic scientists
- Award ID(s):
- 1661206
- PAR ID:
- 10092321
- Date Published:
- Journal Name:
- Science and Public Policy
- Volume:
- 46
- Issue:
- 2
- ISSN:
- 0302-3427
- Page Range / eLocation ID:
- 310 to 320
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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null (Ed.)Abstract We combine infrared absorption and Raman scattering spectroscopies to explore the properties of the heavy transition metal dichalcogenide 1T-HfS 2 . We employ the LO–TO splitting of the E u vibrational mode along with a reevaluation of mode mass, unit cell volume, and dielectric constant to reveal the Born effective charge. We find $${Z}_{{\rm{B}}}^{* }$$ Z B * = 5.3 e , in excellent agreement with complementary first-principles calculations. In addition to resolving the controversy over the nature of chemical bonding in this system, we decompose Born charge into polarizability and local charge. We find α = 5.07 Å 3 and Z * = 5.2 e , respectively. Polar displacement-induced charge transfer from sulfur p to hafnium d is responsible for the enhanced Born charge compared to the nominal 4+ in hafnium. 1T-HfS 2 is thus an ionic crystal with strong and dynamic covalent effects. Taken together, our work places the vibrational properties of 1T-HfS 2 on a firm foundation and opens the door to understanding the properties of tubes and sheets.more » « less