Variationally Calculated Vibrational Energy Levels of Ammonia Adsorbed on a Ni(111) Surface

Abstract

We have calculated vibrational energy levels for an ammonia molecule adsorbed on a Ni(111) surface. An exact kinetic energy operator for the gas phase molecule is combined with a potential energy function that is calculated with the plane-wave density-functional theory. The resulting eigenvalue problem is solved variationally. The vibrational energy levels for a gas phase molecule are also calculated. The calculated adsorption-related shift is +193 cm−1 for the symmetric bend, −54 cm−1 for the asymmetric bend, −68 cm−1 for the symmetric stretch, and −63 cm−1 for the asymmetric stretch, in good agreement with the experimental values +190, −47, −67, and −84 cm−1, respectively.

Mechanism of ammonia decomposition on clean and oxygen-covered Cu (1 1 1) surface: A DFT study

“…1, which combines with Cu (1 1 1) surface on the top site through N atom. Any attempt to find a minimum of energy in the other symmetric sites leads to the top site after complete optimization, which is in agreement with previous theoretical studies of NH 3 adsorption on transition metals [13][14][15][16][17][18][19][20][21][22][25][26][27]. In the preferred adsorption geometry, NH 3 adsorbs on the surface with atomic N downwardly and the C 3 axis of NH 3 is perpendicular to the surface, which is similar to the previous calculation results on Pd (1 1 1) surface [27].…”

“…Bond lengths (Å) Adsorption energies (eV) phenomenon was also confirmed by experiment [6,7,42] and theoretical calculations [13][14][15]23,24,27,33]. For the adsorption of NH 3 on oxygen-covered Cu (1 1 1) surface, it is found that the most stable co-adsorption configuration is that NH 3 adsorbs on the top site and O atom occupies the hcp site ( Fig.…”

“…Armed with these new tools, many researchers have refocused on the interaction between adsorbates and metal surfaces [11][12][13][14][15][16][17][18][19][20][21]. Especially, periodic DFT calculations with the slab model have been a powerful approach to study the adsorption and dissociation of small molecules on the metal surfaces.…”

“…Especially, periodic DFT calculations with the slab model have been a powerful approach to study the adsorption and dissociation of small molecules on the metal surfaces. Much attention has been paid to ascertaining the adsorption and dehydrogenation mechanism of NH 3 on numerous metal surfaces, such as Fe [11,12], Co [12], Ni [13][14][15][16], Ir [5,[17][18][19][20][21][22], Cu [23,24], Pd [25][26][27], Pt [28][29][30][31][32], Au [33]. Most of these works were based on density functional theory (DFT) http calculations.…”

Towards Accurate Spectroscopic Identification of Species at Catalytic Surfaces: Anharmonic Vibrations of Formate on AuPt

“…As assignment of spectra is achieved by comparing measured [2] and computed frequencies, it is clear that the ability to compute accurately vibrational frequencies is important for guiding material design. Today, with rare exceptions [3][4][5][6][7], such assignment is based on uncoupled harmonic frequencies provided by widely used DFT codes [8,9]. Anharmonicity and coupling effects can shift frequencies by dozens cm -1 and hinder assignment [3,10], yet their inclusion in calculations has been too computationally expensive for most labs.…”