Energy and Pressure Calculations for Metallic NH4.
ARMY ARMAMENT RESEARCH AND DEVELOPMENT COMMAND WATERVLIET NY BENET WEAPONS LAB
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It has long been known that the ammonium ion NH4 behaves in many ways like an alkali metal ion. This report dicusses a possible transition under pressure from a mixture of ammonia and hydrogen NH3-12H2 to metallic NH4 in the funny sodium form. This form may be defined as a lattice composed of metallic NH4 ions and s-like electrons one per ion. The ion has the sodium Z number but only seven protons those from N are in the nucleus the other four protons those from the four H atoms from a tetrahedral arrangement around the N nucleus. This tetrahedral arrangement is then approximated by a spherical shell at a radius determined by a variational calculation for the total energy of the tetrahedral ion. The resulting radius lies well out in the ion electron cloud. Since a Wigner-Seitz polyhedra approach is used, no specific lattice structure is considered. We comment on the earlier calculation of Bernal and Massey BM and the more recent calculation of Stevenson. Emphasis is on the BM metallic calculation which we have essentially repeated.
- Physical Chemistry
- Numerical Mathematics