scholarly journals Two Cycling Centers in One Molecule: Communication by Through-Bond Interactions and Entanglement of the Unpaired Electrons

Author(s):  
Maxim Ivanov ◽  
Sahil Gulania ◽  
Anna I. Krylov

<div> <div> <div> <p>Many applications in quantum information science (QIS) rely on the ability to laser-cool molecules. The scope of applications can be expanded if laser-coolable molecules possess two or more cycling centers, i.e., moieties capable of scattering photons via multiple absorption-emission events. Here we employ equation-of-motion coupled-cluster method for double electron attachment (EOM-DEA-CCSD) to study electronic structure of hypermetallic molecules with two alkaline earth metals con- nected by an acetylene linker. We demonstrate that the interaction between two unpaired electrons is weak yet non-negligible, and is reflected in the underlying wavefunction. The electronic structure of the molecules is similar to that of two separated alkali metals, however the interaction between two electrons is largely dominated by through-bond interactions. The communication between the two cycling centers is quantified by the extent of the entanglement of the two unpaired electrons associated with each center. This contribution highlights rich electronic structure of hypermetallic molecules that may advance various applications in QIS and beyond. </p> </div> </div> </div>

2020 ◽  
Author(s):  
Maxim Ivanov ◽  
Sahil Gulania ◽  
Anna I. Krylov

<div> <div> <div> <p>Many applications in quantum information science (QIS) rely on the ability to laser-cool molecules. The scope of applications can be expanded if laser-coolable molecules possess two or more cycling centers, i.e., moieties capable of scattering photons via multiple absorption-emission events. Here we employ equation-of-motion coupled-cluster method for double electron attachment (EOM-DEA-CCSD) to study electronic structure of hypermetallic molecules with two alkaline earth metals con- nected by an acetylene linker. We demonstrate that the interaction between two unpaired electrons is weak yet non-negligible, and is reflected in the underlying wavefunction. The electronic structure of the molecules is similar to that of two separated alkali metals, however the interaction between two electrons is largely dominated by through-bond interactions. The communication between the two cycling centers is quantified by the extent of the entanglement of the two unpaired electrons associated with each center. This contribution highlights rich electronic structure of hypermetallic molecules that may advance various applications in QIS and beyond. </p> </div> </div> </div>


2021 ◽  
Author(s):  
Sahil Gulania ◽  
Anna Krylov

<div> <div> <div> <div> <p>Investigation of microwave-activated CH<sub>4</sub>/H<sub>2 </sub>plasma used in chemical vapor deposition of diamond revealed the presence of electronically excited C<sub>2</sub><sup>-</sup>(B<sup>2</sup>Σ<sub>u</sub><sup>+</sup>). Using high-level electronic structure methods, we investigate electronic structure of C<sub>2</sub>H<sup>-</sup> and suggest possible routes for formation of C<sub>2</sub><sup>-</sup> in the ground (X<sup>2</sup>Σ<sub>g</sub><sup>+</sup>) and excited (B<sup>2</sup>Σ<sub>u</sub><sup>+</sup>) states via electronic resonances. To describe electronically meta-stable states, we employ the equation-of-motion coupled-cluster method augmented by the complex absorbing potential. The resonance wave-functions are analyzed using natural transition orbitals. We identified several resonances in C<sub>2</sub>H<sup>-</sup>, including the state that may lead to C<sub>2</sub><sup>-</sup>(B<sup>2</sup>Σ<sub>u</sub><sup>+</sup>). </p><p> </p> <p></p><p> </p> <p> </p> <p> </p> </div> </div> </div> </div>


2021 ◽  
Author(s):  
Sahil Gulania ◽  
Anna Krylov

<div> <div> <div> <div> <p>Investigation of microwave-activated CH<sub>4</sub>/H<sub>2 </sub>plasma used in chemical vapor deposition of diamond revealed the presence of electronically excited C<sub>2</sub><sup>-</sup>(B<sup>2</sup>Σ<sub>u</sub><sup>+</sup>). Using high-level electronic structure methods, we investigate electronic structure of C<sub>2</sub>H<sup>-</sup> and suggest possible routes for formation of C<sub>2</sub><sup>-</sup> in the ground (X<sup>2</sup>Σ<sub>g</sub><sup>+</sup>) and excited (B<sup>2</sup>Σ<sub>u</sub><sup>+</sup>) states via electronic resonances. To describe electronically meta-stable states, we employ the equation-of-motion coupled-cluster method augmented by the complex absorbing potential. The resonance wave-functions are analyzed using natural transition orbitals. We identified several resonances in C<sub>2</sub>H<sup>-</sup>, including the state that may lead to C<sub>2</sub><sup>-</sup>(B<sup>2</sup>Σ<sub>u</sub><sup>+</sup>). </p><p> </p> <p></p><p> </p> <p> </p> <p> </p> </div> </div> </div> </div>


2020 ◽  
Author(s):  
Soumi Haldar ◽  
Achintya Kumar Dutta

We have presented a multi-layer implementation of the equation of motion coupled-cluster method for the electron affinity, based on local and pair natural orbitals. The method gives consistent accuracy for both localized and delocalized anionic states. It results in many fold speedup in computational timing as compared to the canonical and DLPNO based implementation of the EA-EOM-CCSD method. We have also developed an explicit fragment-based approach which can lead to even higher speed-up with little loss in accuracy. The multi-layer method can be used to treat the environmental effect of both bonded and non-bonded nature on the electron attachment process in large molecules.<br>


1981 ◽  
Vol 14 (15) ◽  
pp. 2165-2173 ◽  
Author(s):  
K Nakamura ◽  
T Hoshino ◽  
M Tsukada ◽  
S Ohnishi ◽  
S Sugano

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