Quantum Monte Carlo study of helium clusters doped with nitrous oxide: Quantum solvation and rotational dynamics

Moroni, Saverio; Blinov, N. S.; Roy, Pierre‐Nicholas

doi:10.1063/1.1774160

Cited by 83 publications

(61 citation statements)

References 14 publications

(17 reference statements)

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“…The filling of a second centered ring starts at N ¼ 18. correlation function can be compared directly to experiment. In earlier work on helium clusters doped with CO 2 [22], N 2 O [7,21], and HCCCN [8], the calculated B was in very good agreement with experiment. The present theoretical values agree remarkably well with experiment and capture the overall behavior of the size evolution of B exp eff .…”

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confidence: 54%

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Molecular Superfluid: Nonclassical Rotations in DopedPara-Hydrogen Clusters

Roy

et al. 2010

Phys. Rev. Lett.

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confidence: 54%

“…We fit these lines in terms of three parameters: band origin, B rotational constant, and D centrifugal distortion constant. Details of the path-integral Monte Carlo calculation method are described elsewhere [7,[21][22][23]. It relies on the so-called worm algorithm [24,25] to account for bosonic exchange.…”

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confidence: 99%

Molecular Superfluid: Nonclassical Rotations in DopedPara-Hydrogen Clusters

Roy

et al. 2010

Phys. Rev. Lett.

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“…It is important to note that the angulon quasiparticle theory described below is substantially simpler -and therefore more transparent -than numerical calculations based on Monte-Carlo algorithms [52,[54][55][56][57][58][69][70][71][72][73][74][75][76][77][78][79].…”

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Fingerprints of angulon instabilities in the spectra of matrix-isolated molecules

Cherepanov

Lemeshko

2017

Phys. Rev. Materials

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The formation of vortices is usually considered to be the main mechanism of angular momentum disposal in superfluids. Recently, it was predicted that a superfluid can acquire angular momentum via an alternative, microscopic route -namely, through interaction with rotating impurities, forming so-called 'angulon quasiparticles ' [Phys. Rev. Lett. 114, 203001 (2015)]. The angulon instabilities correspond to transfer of a small number of angular momentum quanta from the impurity to the superfluid, as opposed to vortex instabilities, where angular momentum is quantized in units of per atom. Furthermore, since conventional impurities (such as molecules) represent three-dimensional (3D) rotors, the angular momentum transferred is intrinsically 3D as well, as opposed to a merely planar rotation which is inherent to vortices. Herein we show that the angulon theory can explain the anomalous broadening of the spectroscopic lines observed for CH3 and NH3 molecules in superfluid helium nanodroplets, thereby providing a fingerprint of the emerging angulon instabilities in experiment.One of the distinct features of the superfluid phase is the formation of vortices -topological defects carrying quantized angular momentum, which arise if the bulk of the superfluid rotates faster than some critical angular velocity [1,2]. Vortex nucleation has been considered to be the main mechanism angular momentum disposal in superfluids [1][2][3][4][5]. Recently, it was predicted that a superfluid can acquire angular momentum via a different, microscopic route, which takes effect in the presence of rotating impurities, such as molecules [6][7][8][9][10][11][12][13]. In particular, it was demonstrated that a rotating impurity immersed in a superfluid forms the 'angulon' quasiparticle, which can be thought of as a rigid rotor dressed by a cloud of superfluid excitations carrying angular momentum [14-21].The angulon theory was able to describe, in good agreement with experiment, renormalization of rotational constants [22,23] and laser-induced dynamics [24,25] of molecules in superfluid helium nanodroplets. One of the key predictions of the angulon theory are the socalled 'angulon instabilities ' [14-16] that occur at some critical value of the molecule-superfluid coupling where the angulon quasiparticle becomes unstable and one or a few quanta of angular momentum are resonantly transferred from the impurity to the superfluid. These instabilities are fundamentally different from the vortex instabilities, associated with the transfer of angular momentum quantised in units of per atom of the superfluid. Furthermore, vortices can be thought of as planar rotors, i.e., the eigenstates of theL z operator. Angulons, on the other hand, are the eigenstates of the total angular momentum operator,L 2 , and therefore the transferred angular momentum is three-dimensional. While vortex instabilities have been subject to several experimental studies in the context of superfluid helium [4,5,[26][27][28][29][30][31], ultracold quantum gases [32][33][34][35][36]...

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“…The turn around of B with N was observed for the first time in 2003, with N 2 O as the dopent molecule. Since then, along with OCS [14] and N 2 O [2,3,[15][16][17][18][19][20], the vibrational and rotational spectra of several other molecules, e.g., HCCCN [9], CO 2 [31], CO [32], etc., for very small N, have also been reported.…”

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confidence: 99%

Quantum dynamics of molecules in 4He nano-droplets: Microscopic superfluidity

et al. 2011

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High resolution spectroscopy of doped molecules in He nano-droplets and clusters gives a signature of superfluidity in microscopic system, termed as microscopic superfluidity. Ro-vibrational spectrum of HeN-M clusters is studied with the help of some important observations, revealed from experiments (viz., localised and orderly arrangement of He atoms, although, being free to move in the order of their locations; individual He atoms can not be tagged as normal/ superfluid, etc.) and other factors (e.g., consideration that the 4 4 4 4 4 He atoms which happen to fall in the plane of rotation of a molecule, render a equipotential ring and thus, do not take part in rotation; etc.) which effect the rotational and vibrational spectrum of the system. This helps us in successfully explaining the experimental findings which state that the rotational spectrum of clusters have sharp peaks (indicating that the molecule rotates like a free rotor) and moment of inertia and vibrational frequency shift have a non-trivial dependence on N.

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Quantum Monte Carlo study of helium clusters doped with nitrous oxide: Quantum solvation and rotational dynamics

Cited by 83 publications

References 14 publications

Molecular Superfluid: Nonclassical Rotations in DopedPara-Hydrogen Clusters

Molecular Superfluid: Nonclassical Rotations in DopedPara-Hydrogen Clusters

Fingerprints of angulon instabilities in the spectra of matrix-isolated molecules

Quantum dynamics of molecules in 4He nano-droplets: Microscopic superfluidity

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