Choice Of Wave Function Research Articles

LONG RANGE FORCES BETWEEN HYDROGEN MOLECULES

Long range forces between two hydrogen molecules are calculated by using methods developed by Massey and Buckingham. Several terms omitted by them and a corrected numerical factor greatly change results for the van der Waals energy but do not affect their results for the static quadrupole–quadrupole energy. By using seven approximate ground state H2 wave functions information is obtained regarding the dependence of the van der Waals energy on the choice of wave function. The value of this energy averaged over all orientations of the molecular axes is found to be approximately −11.0 R−6 atomic units, a result in close agreement with semiempirical values.

Mesonic Corrections to the Quadrupole Moment of the Deuteron

Mesonic corrections to the quadrupole moment of the deuteron are calculated by means of the method of Tamm and Dancoff. Only the two-nucleon and two-nucleon\char22{}one-meson amplitudes are included. The first is associated with a phenomenological wave function for the deuteron, the second yielding a correction to the quadrupole moment. A correction exists even in neutral scalar theory, and for pseudoscalar (pseudoscalar) symmetric theory the result in adiabatic approximation to second order is $\ensuremath{\Delta}Q=3.1$ percent or $\ensuremath{\Delta}Q=\ensuremath{-}0.7$ percent, depending on choice of wave functions (assuming $\frac{{g}^{2}}{4\ensuremath{\pi}}=10$). Contributions from multiple meson amplitudes are examined, and for a hard-core deuteron function they are shown to contribute only slightly.

A Quantum Mechanical Treatment of the Lithium Fluoride Crystal

A simplified quantum-mechanical model for the LiF crystal is described. The lattice parameter, cohesive energy and compressibility are calculated using three different choices of wave function for the fluorine ion in the crystal; these are (i) the Hartree wave functions for the free ion F-, (ii) wave functions orthogonalized to the 1s-orbitals of the six nearest neighbour lithium ions, (iii) functions similar to (ii) but based on wave functions for the free ion which have been contracted to give agreement with the diamagnetism of F-. The results obtained in (i) are in fair agreement with the empirical values Large discrepancies are observed when the more complete wave functions (ii) are employed. This is taken as indicating that the Hartree wave functions for the free ion are too diffuse and the results of the third calculation, which agree well with experiment, substantiate this interpretation.