Periodic quantum mechanical simulation of the He–MgO(100) interaction potential

Martínez-Casado, Ruth; Mallia, Giuseppe; Usvyat, Denis; Maschio, Lorenzo; Casassa, Silvia; Schütz, Martin; Harrison, N. M.

doi:10.1063/1.3517868

Cited by 36 publications

(63 citation statements)

References 29 publications

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“…[16]). Even with a more rigorous MP2 description, the dispersion interaction with helium is grossly underestimated and cannot be used without higher-order correlation corrections [15,17]. A finite cluster approach facilitates, in principle, an ab initio treatment that can be extended to arbitrary accuracy, yet the truncation to finite cluster size results in the neglect of long-range effects and may consequently also severely compromise the accuracy at the energy scale of He-surface interaction energies.…”

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confidence: 99%

“…It has recently been established [15,26,27] that the MP2 level of theory significantly underestimates the adsorption energy of noble gases on the MgO surface, and especially so for He. This implies that the required accuracy cannot be reached without higher-order corrections to MP2.…”

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confidence: 99%

“…In principle it can be used for calculating * r.martinezcasado@imperial.ac.uk † denis.usvyat@chemie.uni-regensburg.de the repulsive wall at the qualitative level [11][12][13], but for the potential well and the corresponding bound states lack of an accurate description of the dispersion interaction renders DFT too unreliable to be used as a predictive theory. An empirical a posteriori dispersion correction, which explicitly introduces the van der Waals-like component, can serve as a practical remedy to this problem [14], yet the crudeness and empiricism of this approach hinder quantitatively accurate first-principle predictions [15,16] (for a striking example see Fig. 5 in Ref.…”

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confidence: 99%

“…The three-layer slab was extrapolated to the bulk limit by employing the slab replication technique [20]. Further technical details of the calculations are given in Appendix A.It has recently been established [15,26,27] that the MP2 level of theory significantly underestimates the adsorption energy of noble gases on the MgO surface, and especially so for He. This implies that the required accuracy cannot be reached without higher-order corrections to MP2.…”

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confidence: 99%

“…A reasonably large atom centered Gaussian basis set of triple-zeta quality for Mg and oxygen, and quadruple-zeta quality for He, augmented with diffuse orbitals (for oxygen and He atoms) was used (details of the basis set can be found in Ref. [15]). For further reference we denote this basis as AVTZ.…”

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confidence: 99%

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Approaching an exact treatment of electronic correlations at solid surfaces: The binding energy of the lowest bound state of helium adsorbed on MgO(100)

et al. 2014

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In this work we employ ab initio electronic structure theory at a very high level to resolve a long standing experimental controversy; the interaction between helium and the MgO (100) surface has been studied extensively by other groups, employing diverse experimental approaches. Nevertheless, the binding energy of the lowest bound state is still unclear: the existence of a state at around −5.5 meV is well established but a state at −10 meV has also been reported. The MgO (100)-He system captures the fundamental physics involved in many adsorption problems; the weak binding is governed by long-range electronic correlation for which a fully predictive theory applicable to the solid state has been elusive. The above-mentioned experimental controversy can now be resolved on the basis of the calculations presented in this work. We performed three-dimensional vibrational dynamics calculations on a highly accurate potential-energy surface. The latter was constructed using a method which systematically approaches the exact limit in its treatment of electronic correlation. The outcome is clear: our calculations do not support the existence of a bound state around −10 meV. The interaction between molecules and crystalline surfaces is of great fundamental and technological interest and is extensively studied both experimentally and theoretically [1][2][3]. One particular example is physisorption and scattering of helium atoms on oxide surfaces. In the last two decades the latter process, employing molecular-beam techniques, has been developed into a powerful tool for the analysis of surface structure and dynamics [4][5][6][7][8]. It is particularly useful for studying insulating surfaces, such as MgO [4,9]. At close proximity the helium-surface interaction potential is dominated by the exponentially growing corrugated repulsive wall, which is a consequence of the mutual exchange repulsion between the helium and surface electron densities. The repulsive potential is two-dimensional (2D) corrugated and leads to a complicated diffraction pattern for helium scattered from the surface. In the range of intermediate He-surface distances, there exists a very shallow attractive potential due to the weak van der Waals interactions, which drops off with distance from the surface as 1/z 3 [10]. Such a potential can support several bound states (in fact several 2D bands of bound states), which correspond to vibrational levels of helium atoms physisorbed on the surface.The delicacy of the balance between different components of the helium-surface interaction makes quantitatively accurate theoretical predictions of the behavior of helium atoms on the surface extremely difficult. Standard density functional theory (DFT), which is the common tool in solid-state simulations (i.e., local-density approximation, generalized gradient approximation, or hybrids), does not capture van der Waals dispersion. In principle it can be used for calculating * r.martinezcasado@imperial.ac.uk † denis.usvyat@chemie.uni-regensburg.de the repulsive wall at th...

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confidence: 99%