Calculations of 14N and 2H Nuclear Quadrupolar Coupling Constants for Liquid Ammonia

Abstract

Abstract Nitrogen (14N) and deuterium (2H) nuclear quadrupolar coupling constants, ϰ(14N) and ϰ(2H), have been calculated for liquid ammonia at 197 K, 232 K, and 271 K, using a combination of molecular dynamics simulations and ab initio molecular orbital calculations. The basis set and cluster size dependence of the calculated results has been examined. The calculated value of ϰ(14N) for liquid ammonia at 197 K, -3.45 MHz, is found to be close to the accepted solid-state value. At 232 K and 271 K, the magnitudes of the calculated values are about 5 - 10% greater: -3.56 MHz and -3.67 MHz, respectively, but still well below the accepted gas-phase value, -4.09 MHz. The calculated values of ϰ (2H) for liquid ammonia are by about 20% smaller than the corresponding values calculated for the gas-phase monomer. On the basis of the calculations presented here and those of previous workers it is clear that the accepted experimental value of ϰ(2H) for solid ammonia-d3 is too small.