Early work was in theoretical polarography (with J. Koutecký) on
polarographic kinetic currents. This was followed by
experimental work in high-resolution optical spectroscopy (with D. A. Ramsay)
leading to the first analysis of the rotational fine structure of the
electronic spectra of a truly polyatomic molecule and a determination
of the first singlet excited state geometry of glyoxal.
Paldus' principal work concerns quantum chemical methodology and its applications
(several with J. Čížek):
Formulation of stability conditions for Hartree-Fock solutions and introduction of concepts of the singlet, doublet, triplet, etc. stability.
First ab initio exploitation of coupled-cluster theory including an approximate account of triples.
Exploitation of the field-theoretic and diagrammatic methods in quantum chemistry, particularly in many-electron correlation problem.
Formulation of algebraic techniques involving both compact and non-compact Lie groups or algebras, in particular the unitary group and Clifford algebra approaches, and their exploitation in large-scale configuration interaction calculations, as well as in coupled-cluster and valence-bond approaches.
Property calculations via Green function, MBPT, and coupled-cluster linear response techniques.
Formulation of externally-corrected coupled-cluster approaches (with X. Li).
Development of both valence-universal and state-specific multi-reference coupled-cluster approaches, in particular the exact formulation of valence universality (with B. Jeziorski) and the formulation of general-model-space coupled-cluster approaches (with X. Li).
Multi-electron quantum dots and the concept of a conjugate Fermi-hole (with T. Sako and G.H.F. Diercksen).