Self-consistent field proton densities in XH₄molecules

The Decoupling of Electronic and Nuclear Motions in the Isolated Molecule Schrödinger Hamiltonian

“…It is easy to imagine how, in principle, such calculations might be carried out for ammonia using the translationally invariant bond vector coordinates. However, it seems that the only calculations of this kind that have ever been done, (for examples, see Thomas [69], Petit and Dancura [70], and Monkhorst [71]) have taken the electronic origin as fixed so that they are essentially one centre calculations. The results are insufficient to enable any firm conclusions to be drawn.…”

“…This sort of thing has been attempted in work referred to earlier [69, 70,71], although not in coordinates fixed in the body but simply in translation-free coordinates. Although it has been quite successful in few-electron diatomics [ 8 5 ] , it has not been successful in polyatomics.…”

Thermal and mechanical properties of some fcc transition metals

“…We use the program SIMULATOR developed by Ç agın that employs state of the art MD algorithms based on extended Hamiltonian formalisms emerging from the works of Anderson, 18 Parinello and Rahman, 19 Nosé, 20 Hoover, 21 and Ç agın. 22 A 500 atoms cubical system is used and the simulation started with atoms randomly distributed on a fcc lattice.The system is thermalized starting from 0 K to the target temperature using a constant enthalpy and constant pressure ͑NHP͒ ensemble by slowly heating while scaling velocities to increment the temperature of 1 K/step over the specific number of steps depending on the target temperature. This is followed by strict velocity scaling at each target temperature.…”

The Concept of Molecular Structure

“…One could realise it in a linear combination-of-basis-functions manner if that seemed desirable. Of course, given the possible complexities of the potential and the kinetic energy operator, it would be a very tricky task in practice, but it is possible to see how such an approach could be carried through and indeed it has been attempted for ammonia [20] (see also [21,22]). …”