We present ab initio Hartree-Fock lattice calculations on adenine, guanine and hypoxanthine, and some pyrimidines, including cytosine and uracil derivatives. The electric field gradients at the nitrogen centres are related to NQR experimental determinations of nuclear quadrupole coupling constants. The calculations were performed as lattice calculations in the unit cell environment, with 6-31G ...

Increasing numbers of HIV infected patients along with severe treatment-associated complications and related deaths make the AIDS pandemic [1]. These inhibitors reduced the virus proliferation and this success made the HIV aspartic protease the prime target for AIDS therapies [2]. In this study, we present the first account of pentacycloundecane (PCU) lactam-peptide based HIV protease inhibitor...

The nuclear quadrupole interaction (NQI) in layered transition metal dichalcogenides usually decreases linearly with increasing temperature [1]. This behaviour was attributed to anisotropic lattice vibrations and is the two-dimensional analog of the Tpower law in three dimensions [2], In order to investigate the origin of this linear power law further we choose another layered compound, namely ...

Powder Zeeman NQR spectra of Sb in Sb(C6H5)3 were studied by means of a computer simulation and an experiment. TheSb nucleus has spin 7/2. There are two non-equivalentSb atoms in the crystal of Sb(C6H5)3, so that there are two series of three transition lines (higher series: 1h, 2h, 3h; lower series: 1l, 2l, 3l). The powder Zeeman spectra for 1h, based on the transition between the levels mI = ...

The electric quadrupole coupling constant of the ground state of 37K(Iπ = 3/2+, T1/2 = 1.22 s) in a tetragonal KH2PO4 single crystal was measured to be |eqQ/h| = 2.99± 0.07 MHz using the β-ray detecting nuclear quadrupole resonance technique. The electric quadrupole moment of 37K was determined to be |Q(37K)| = 10.6 ± 0.4 efm2, where the known electric quadrupole coupling constant of stable 39K...

The nuclear spins of ionized donors in silicon have become an interesting quantum resource due to their very long coherence times. Their perfect isolation, however, comes at a price, since the absence of the donor electron makes the nuclear spin difficult to control. We demonstrate that the quadrupolar interaction allows us to effectively tune the nuclear magnetic resonance of ionized arsenic d...

Shifts from the expected nuclear magnetic resonance frequencies of antimony and bismuth donors in silicon of greater than a megahertz are observed in electrically detected magnetic resonance spectra. Defects created by ion implantation of the donors are discussed as the source of effective electric field gradients generating these shifts via quadrupole interaction with the nuclear spins. The ex...