Does metallic ammonium exist?

@article{Stevenson1975DoesMA,
  title={Does metallic ammonium exist?},
  author={David J. Stevenson},
  journal={Nature},
  year={1975},
  volume={258},
  pages={222-223}
}
THE ammonium ion NH4+ behaves in many ways like an alkali metal ion. This led Ramsey1 to propose that monovalent ammonium metal (NH4+ ions immersed in an almost uniform, degenerate sea of electrons) is stable at pressures much lower than typical insulator–metal transition pressures2 of megabars ∼1011 Pa (105 Pa = 1 bar). Subsequently, it was estimated3 that the transition from a mixture of NH3 and H2 molecules to metallic ammonium, occurs at a pressure of less than 2.5×1010 Pa. If this estimate… 

Superalkali behavior of ammonium (NH4+) and hydronium (OH3+) cations: a computational analysis

Superalkalis are unusual species having ionization energy (IE) lower than that of alkali atom. The examples of typical superalkali cations include FLi2+, OLi3+, NLi4+, etc. Ammonium (NH4+) and

Pentazole and Ammonium Pentazolate: Crystalline Hydro-Nitrogens at High Pressure.

Two new crystalline compounds, pentazole (N5H) and ammonium pentazolate (NH4)(N5), both featuring cyclo-N5- are discovered using a first-principles evolutionary search of the nitrogen-rich portion of

Computational Discovery of Energetic Polynitrogen Compounds at High Pressure

High-nitrogen-content energetic compounds containing multiple N-N bonds are an attractive alternative towards developing new generation of environmentally friendly, and more powerful energetic

Design of the NnH3n+1+ series of “non-metallic” superalkali cations

A new series of non-metallic superalkali cations, NnH3n+1+ by using ammonium (NH4+) cations, possessing vertical electron affinity (EAv), 4.39 eV for n = 1 to 2.39 eV for n = 5 has been proposed.

Computational Discovery of New High-Nitrogen Energetic Materials

High-nitrogen-content energetic compounds containing multiple N–N bonds are an attractive candidate for new generation of environmentally friendly, and more powerful energetic materials. High-N

Sub-Doppler slit jet infrared spectroscopy of astrochemically relevant cations: The NH stretching mode in ND3H.

TLDR
The results allow us to predict several low-J pure rotational transitions of ND3H+, which it is hoped will support future studies of this important ion in laboratory and astronomical rotational spectroscopy.

Role of central core and methyl substitutions in XH4-x(CH3)x (X = N, P, As; x = 0–4) superalkalis: an ab initio study

Superalkalis are known for their lower ionization energy than alkali atoms. In the last four decades, a lot of exploration has been done to enrich the superalkali series. In this work, we report the

Sub-Doppler slit jet infrared spectroscopy of astrochemically relevant cations: Symmetric (ν1) and antisymmetric (ν6) NH stretching modes in ND2H2.

TLDR
This work permits prediction of precision microwave/mm-wave transitions, which should be invaluable in facilitating ongoing spectroscopic searches for partially deuterated ammonium cations in interstellar clouds and star-forming regions of the interstellar medium.

Statistical Contact Model for Confined Molecules

A theory that describes in a realistic form a system of atoms under the effects of temperature and confinement is presented. The theory departs from a Lagrangian of the Zwanzig type and contains the

Diverse Chemistry of Stable Hydronitrogens, and Implications for Planetary and Materials Sciences

TLDR
Surprisingly, high pressure stabilizes a series of previously unreported compounds with peculiar structural and electronic properties, and the predicted phase diagram of the N-H system also provides a reference for synthesis of high-energy-density materials.

References

SHOWING 1-10 OF 12 REFERENCES

On the Herzfeld Theory of Metallization. Application to Rare Gases, Alkali Halides, and Diatomic Molecules

In 1927 Herzfeld proposed a criterion which predicted that an element would become metallic when its molar volume became equal to or less than R, its molar refractivity. We have inspected this

A theoretical analysis of the shock compression experiments of the liquid hydrogen isotopes and a prediction of their metallic transition

Shock compression experiments in which the liquid hydrogen isotopes were compressed as much as sevenfold in density to pressures of the order of 900 kbar are analyzed to obtain an effective

On the Constitutions of the Major Planets

Summary The internal constitutions of the major planets are investigated on the basis of the atomic theory of solids. The starting point of the investigation is the theoretical pressure-density

An Improved Calculation of the Energies of Metallic Li and Na

The method of calculation used in the present work is a modification of that used by Wigner and Seitz in their original calculations of the energies of metallic Li and Na. The main difference lies in

Compression and Phase Transitions of Solid NH3, SiF4, H2S, and CF4

Isothermal PV curves of solid NH3, SiF4, H2S, and CF4 have been observed by the direct piston displacement method up to pressures of 20 000 kg/cm2 at various temperatures between 100° and 200°K.

Theoretical high-pressure equations of state including correlation energy.

The correlation energy of the electron gas is treated as a perturbation on the total free energy computed for the zero-temperature Thomas-Fermi-Dirac (TFD) model of a solid. The contribution to the

The Calculation of Electronic Properties of BH4-, CH4 and NH4+ using One-centre Self-consistent Field Wave Functions

Self-consistent field wave functions are computed for the isoelectronic systems BH4-, CH4 and NH4+ for various values of the bond length using the one-centre method. These wave functions are used to