<i>Ab initio</i> study of HCl and HF interaction with crystalline ice. I. Physical adsorption

Bussolin, Giovanni; Casassa, Silvia; Pisani, Cesare; Ugliengo, Piero

doi:10.1063/1.475340

Cited by 72 publications

(86 citation statements)

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“…has been computed for ferroelectric and antiferroelectric ice XI and >20 ice Ih structures. Consistent with previous studies and, of course, because it possesses a dipole along the surface normal, the ferroelectric ice XI surface is unstable [8,19] [7]). For ice Ih, however, we do not get a unique value for .…”

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confidence: 73%

Surface Energy and Surface Proton Order of IceIh

et al. 2008

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Ice Ih is comprised of orientationally disordered water molecules giving rise to positional disorder of the hydrogen atoms in the hydrogen bonded network of the lattice. Here we arrive at a first principles determination of the surface energy of ice Ih and suggest that the surface of ice is significantly more proton ordered than the bulk. We predict that the proton order-disorder transition, which occurs in the bulk at $72 K, will not occur at the surface at any temperature below surface melting. An order parameter which defines the surface energy of ice Ih surfaces is also identified. DOI: 10.1103/PhysRevLett.101.155703 PACS numbers: 64.60.Cn, 68.47.Àb, 82.65.+r Ice Ih, the normal form of ice, is built from water molecules arranged on a tetrahedral lattice, subject to a set of rules known as the ice rules [1]. These rules allow for orientational disorder of the molecules, which is discussed in terms of the positional disorder of the hydrogen atoms, a phenomenon known as proton disorder. Under ambient pressures, ice Ih is the stable phase down to $72 K [2], below which a proton ordered (ferroelectric) phase known as ice XI becomes the ground state. In practice, the ordering transformation from ice Ih to the lowest total energy ice XI phase rarely happens since, as the temperature is lowered to the transition temperature, proton motion comes to a halt. This leaves the crystal out of equilibrium at below 72 K with residual entropy. Indeed, ice Ih is so resistant to transforming from ice Ih into ice XI that a dopant that accelerates proton rearrangement (KOH) is usually added to make it occur.Given the experimental difficulties in probing the ice Ih-XI transition, molecular simulations are very useful [3][4][5]. In particular, in a tour de force study, density functional theory (DFT) was combined with a framework based on graph invariants to simulate the bulk ice Ih-XI transition. A transition temperature of 98 K was predicted, within 30 K of the experimental transition [5]. This demonstrates that DFT is appropriate for tackling the subtle question of proton order and disorder in ice, something which cannot necessarily be said about the many empirical potentials that otherwise describe many parts of the phase diagram of water well [6].Unlike in bulk ice, the understanding of the energetics of proton order at the surface is in its infancy [7,8]. This is true despite widespread interest in ice surfaces at low temperatures, motivated mainly by their catalytic role in atmospheric chemistries such as ozone depletion (see, e.g., [9]). Indeed, the understanding is so incomplete that the value of the surface energy-one of the most important quantities of any material-is well-established neither experimentally nor theoretically and how it is influenced by proton order is not known. Here, in arriving at an ab initio determination of the surface energy of the (0001) (basal plane) of ice Ih, we demonstrate that the energetics of proton ordering differs significantly at the surface compared to the bulk. Indeed, the range of...

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confidence: 73%

Surface Energy and Surface Proton Order of IceIh

et al. 2008

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“…Among the different structures possible, we considered only the apolar variety. On the one hand, it seems the most plausible arrangement according to the crystallization conditions in the ISM; on the other hand, it is computationally justified because only apolar structures can generate slabs that are stable (Bussolin et al 1998), reproduce the bulk properties, and have a balanced distribution of alternate hydrogen and oxygen sites at their surfaces (for a complete discussion, see Casassa et al 2005). The model unit (Cell 1) contains two bilayers (Fig.…”

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confidence: 99%

Differential adsorption of CHON isomers at interstellar grain surfaces

Lattelais

Pauzat

Ellinger

et al. 2015

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Context. The CHON generic chemical formula covers different isomers such as isocyanic acid (HNCO), cyanic acid (HOCN), fulminic acid (HCNO), and isofulminic acid (HONC); the first three have been identified in a large variety of environments in the interstellar medium (ISM). Several phenomena could be at the origin of the observed abundances, such as different pathways of formation and destruction involving gas phase reactions with different possible activation barriers and/or surface processes depending on the local temperature and the nature of the support. Aims. The scope of this article is to shed some light on the interaction of the CHON isomers with interstellar grains as a function of the nature of the surface and to determine the corresponding adsorption energies in order to find whether this phenomenon could play a role in the abundances observed in the ISM. Methods. The question was addressed by means of numerical simulations using first principle periodic density functional theory (DFT) to represent the grain support as a solid of infinite dimension. Results. Regardless of the nature of the model surface (water ice, graphene, silica), two different classes of isomers were identified: weakly bound (HNCO and HCNO) and strongly bound (HOCN and HONC), with the adsorption energies of the latter group being about twice those of the former. The range of the adsorption energies is (from highest to lowest) HOCN > HONC > HNCO > HCNO. They are totally disconnected from the relative stabilities, which range from HNCO > HOCN > HCNO > HONC. Conclusions. The possibility of hydrogen bonding is the discriminating factor in the trapping of CHON species on grain surfaces. Whatever the environment, differential adsorption is effective and its contribution to the molecular abundances should not be ignored. The theoretical adsorption energies provided here could be profitably used for a more realistic modeling of molecule-surfaces interactions.

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“…Among the different structures possible, we considered only the apolar variety. On the one hand, it seems the most plausible arrangement according to the crystallisation conditions in the ISM and on the other hand, it is computationally justified because only apolar structures can generate slabs that are stable (Bussolin et al 1998), reproduce the bulk properties, and at their surfaces have a balanced distribution of alternate hydrogen and oxygen sites (for a complete discussion see Casassa et al 2005).…”

Section: Computational Backgroundmentioning

confidence: 99%

Differential adsorption of complex organic molecules isomers at interstellar ice surfaces

Lattelais

Bertin

Mokrane

et al. 2011

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Context. Over 20 of the ∼150 different species detected in the interstellar and circumstellar media have also been identified in icy environments. For most of the species observed so far in the interstellar medium (ISM), the most abundant isomer of a given generic chemical formula is the most stable one (minimum energy principle -MEP) with few exceptions such as, for example, CH 3 COOH/HCOOCH 3 and CH 3 CH 2 OH/CH 3 OCH 3 , whose formation is thought to occur on the icy mantles of interstellar grains. Aims. We investigate whether differences found in the compositions of molecular ices and the surrounding gas phase could originate from differences between the adsorption of one isomer from that of another at the ice surface. Methods. We performed a coherent and concerted theoretical/experimental study of the adsorption energies of the four molecules mentioned above, i.e. acetic acid (AA)/methyl formate (MF) and ethanol (EtOH)/dimethyl ether (DME) on the surface of water ice at low temperature. The question was first addressed theoretically at LCT using solid state periodic density functional theory (DFT) to represent the organized solid support. The experimental determination of the ice/molecule interaction energies was then carried out independently by two teams at LPMAA and LERMA/LAMAp using temperature programmed desorption (TPD) under an ultra-high vacuum (UHV) between 70 and 160 K. Results. For each pair of isomers, theory and experiments both agree that the most stable isomer (AA or EtOH) interacts more efficiently with the water ice than the higher energy isomer (MF or DME). This differential adsorption can be clearly seen in the different desorption temperatures of the isomers. It is not related to their intrinsic stability but instead to both AA and EtOH producing more and stronger hydrogen bonds with the ice surface. Conclusions. We show that hydrogen bonding may play an important role in the release of organic species from grains and propose that, depending on the environment, differential adsorption should not be rejected as a possible way of interpreting MEP exceptions.

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Ab initio study of HCl and HF interaction with crystalline ice. I. Physical adsorption

Cited by 72 publications

References 50 publications

Surface Energy and Surface Proton Order of IceIh

Surface Energy and Surface Proton Order of IceIh

Differential adsorption of CHON isomers at interstellar grain surfaces

Differential adsorption of complex organic molecules isomers at interstellar ice surfaces

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