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Updated: May 10, 2026

Ammonia Synthesis at Low Pressure
Published on: August 23, 2017
Equation of state and phase diagram of ammonia at high pressures from ab initio simulations
Mandy Bethkenhagen1, Martin French, Ronald Redmer
1Institut für Physik, Universität Rostock, 18051 Rostock, Germany.
Abstract:
We present an equation of state as well as a phase diagram of ammonia at high pressures and high temperatures derived from ab initio molecular dynamics simulations. The predicted phases of ammonia are characterized by analyzing diffusion coefficients and structural properties. Both the phase diagram and the subsequently computed Hugoniot curves are compared to experimental results. Furthermore, we discuss two methods that allow us to take into account nuclear quantum effects, which are of considerable importance in molecular fluids. Our data cover pressures up to 330 GPa and a temperature range from 500 K to 10,000 K. This regime is of great interest for interior models of the giant planets Uranus and Neptune, which contain, besides water and methane, significant amounts of ammonia.
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