Electronic properties of liquid ammonia: A sequential molecular dynamics/quantum mechanics approach

Abstract

Electronic structures of c-plane and a-plane AlN/ZnO heterointerfaces determined by synchrotron radiation photoemission spectroscopy Appl. Phys. Lett. 97, 252111 (2010) Theoretical predictions of trends in spectroscopic properties of gold containing dimers of the 6p and 7p elements and their adsorption on gold J. Chem. Phys. 133, 104304 (2010) Additional information on J. Chem. Phys. The electronic properties of liquid ammonia are investigated by a sequential molecular dynamics/ quantum mechanics approach. Quantum mechanics calculations for the liquid phase are based on a reparametrized hybrid exchange-correlation functional that reproduces the electronic properties of ammonia clusters ͓͑NH 3 ͒ n ; n =1-5͔. For these small clusters, electron binding energies based on Green's function or electron propagator theory, coupled cluster with single, double, and perturbative triple excitations, and density functional theory ͑DFT͒ are compared. Reparametrized DFT results for the dipole moment, electron binding energies, and electronic density of states of liquid ammonia are reported. The calculated average dipole moment of liquid ammonia ͑2.05± 0.09 D͒ corresponds to an increase of 27% compared to the gas phase value and it is 0.23 D above a prediction based on a polarizable model of liquid ammonia ͓Deng et al., J. Chem. Phys. 100, 7590 ͑1994͔͒. Our estimate for the ionization potential of liquid ammonia is 9.74± 0.73 eV, which is approximately 1.0 eV below the gas phase value for the isolated molecule. The theoretical vertical electron affinity of liquid ammonia is predicted as 0.16± 0.22 eV, in good agreement with the experimental result for the location of the bottom of the conduction band ͑−V 0 = 0.2 eV͒. Vertical ionization potentials and electron affinities correlate with the total dipole moment of ammonia aggregates.

Ferroelectric tunnel junctions with graphene electrodes

“…As representative values we assume E F À E C ¼ 2.5 eV for LSMO and E F À E C ¼ 0.5 eV for graphene. Electronic properties of ammonia are characterized by the energy gap between the LUMO and HOMO states of about 10 eV 35 . For the Fermi energy lying in the middle of the gap, the effective potential barrier produced by ammonia is U A ¼ 5 eV.…”

Continuum, discrete, and explicit solvation models for describing the low‐lying absorption spectrum of the pterin acid in aqueous environment

“…This model is referred to as Sþ29Wþ225PC and involves super-molecular structures with as much as 374 electrons. Previous experiences [42] have indicated that the electrostatic embedding has an stabilizing effect on the dependence of the results with the number of explicit solvent molecules included. Thus, we expect that using solvent molecules well beyond the first solvation shell will have little effect on the transition energies reported here.…”

From the (NH3)2–5 clusters to liquid ammonia: Molecular dynamics simulations using the NVE and NpT ensembles

“…In fact, Almeida et al [28], considering embedding clusters of different size, calculate dipole moment values equal to 2.00 D, 2.01 D and 2.05 D for the NH 3 monomer in the dimer, the pentamer and liquid ammonia, respectively. The same values have been used in the present study, while the corresponding values for the trimer and the tetramer have been interpolated from 2.00 D and 2.01 D. The increase of the dipole moment going from gas phase to liquid was also evidenced for water from a combined experimental and theoretical study of small clusters (up to six monomers) [36] and it was applied successfully to study both, some small clusters and liquid water [30].…”

“…Due to both the mentioned separability between electrostatic and nonelectrostatic contributions and the flexibility of the ILJ function, V nel can be combined with different descriptions of the electrostatic contribution. In the present investigation we use a simple 4-site for NH 3 , whose charges are selected taking into account the increase of about a 27% of the monomer dipole moment (μ) in liquid environment in comparison with the gas phase value [28].…”