One of the central challenges of computational molecular investigation is the solution of the
time-independent, nonrelativistic BornÀ Oppenheimer electronic Schrödinger equation. For …

The variational method complemented with the use of explicitly correlated Gaussian basis
functions is one of the most powerful approaches currently used for calculating the …

Theoretical chemistry could be seen as a bridge from the real physics of the physicists to the
real chemistry of the experimental chemists. We hence expect that any measurable property …

The basis set superposition effect (BSSE) is a simple concept, and its validity is almost
universally accepted. So is the counterpoise method to correct for it. The idea is that the …

Since the early work of Hylleraas on the helium atom, 1 it has been common knowledge that,
to accurately account for the interaction between the electrons in an atom or a molecule …

We have performed very accurate quantum mechanical calculations of the five lowest S
states of the beryllium atom. In the nonrelativistic part of the calculations we used the …

Structural information is extracted from the all-particle (non-Born–Oppenheimer) wave
function by calculating radial and angular densities derived from n-particle densities. As a …

We report absolute frequency measurements on the three excited-state transitions
connecting the 2 p 2 (3 P) 3 s 2 P 1/2, 3/2 and 2 p 2 (3 P) 3 p 2 D 3/2, 5/2∘ states in neutral N …

We compare the explicitly correlated Hylleraas and exponential basis sets in the evaluations
of ground state of Li and Be+. Calculations with Hylleraas functions are numerically stable …

Variational calculations have been carried out for the ground states of several members of
the beryllium isoelectronic series using a standard Hylleraas approach involving Slater-type …