First principles study of structural stability, electronic and related properties of (NH4)2SO4

Abstract

The electronic structure and related physical properties of crystalline ammonium sulfate, (NH 4 ) 2 SO 4 , have been studied using the first principles code CRYSTAL06 at the B3LYP level of theory. The title compound has been found to possess one stable and three metastable configurations, all within the polar space group Pna2 1 (no. 33). Two of the metastable polymorphs are newly predicted and have not yet been observed experimentally.The different configurations show considerably varying magnitudes of the spontaneous polarization P s . All coefficients of the elastic stiffness tensor, c kl , and elastoelectrical tensor, e ki have been calculated for the first time and have been found to agree satisfactorily with experimental data, as far as available.

DFT-basedab initiostudy of structural and electronic properties of lithium fluorooxoborate LiB6O9F and experimentally observed second harmonic generation

“…., 6), and coefficients of the elastoelectric tensor e ik (i = 1, 2, 3) were calculated using the same approach as in earlier studies. 11,12 The coupled perturbed Kohn-Sham method (CPKS) was used to compute linear optical properties. 13 The calculations were done within the framework of the hybrid functional B3LYP for the exchange and correlation part of the Hamiltonian.…”

Ionicity and birefringence of α-LiNH4SO4crystals: ab initio DFT study, X-ray spectroscopy measurements

“…Similar studies have been recently published for other crystals of the ABCX 4 group, such as: Rb 2 ZnCl 4 , 17 K 2 ZnCl 4 , 18 K 2 SO 4 , 19 (NH 4 ) 2 SO 4 (ref. 20) etc. In order to verify the data of the present band structure calculations, we have explored opportunities of the X-ray photoelectron spectroscopy (XPS) and X-ray emission spectroscopy (XES) methods to study the LiNH 4 SO 4 compound through the XPS core-level and valence-band spectra as well as the XES bands representing energy distribution of the O 2p and N 2p states.…”

Investigating Freezing Point Depression and Cirrus Cloud Nucleation Mechanisms Using a Differential Scanning Calorimeter

“…The DSC temperature calibration was verified by measuring the melting point of Indium metal (∼429.7 K). An additional check of the temperature calibration was carried out at low temperatures by measuring the ferroelectric phase transition of bulk ammonium sulfate (∼223.0 K). , …”

“…An additional check of the temperature calibration was carried out at low temperatures by measuring the ferroelectric phase transition of bulk ammonium sulfate (∼223.0 K). 4,5 After the DSC temperature calibration was verified, aqueous ammonium sulfate solutions containing various amounts of solute were emulsified in a mineral oil/lanolin matrix according to a procedure modified from Pinti et al 6 First, aqueous ammonium sulfate/mineral oil/lanolin samples were created using double distilled water, ammonium sulfate (≥99.0%), mineral oil (100% saturated hydrocarbon) and lanolin (<0.1% water). All compounds were purchased from Sigma-Aldrich.…”