  Leptoquark models may explain deviations from the Standard Model observed in
decay processes involving heavy quarks at high-energy colliders. Such models
give rise to low-energy parity- and time-reversal-violating phenomena in atoms
and molecules. One of the leading effects among these phenomena is the
nucleon-electron tensor-pseudotensor interaction when the low-energy
experimental probe uses a quantum state of an atom or molecule predominantly
characterized by closed electron shells.
  In the present paper the molecular interaction constant for the
nucleon-electron tensor-pseudotensor interaction in the thallium-fluoride
molecule -- used as such a sensitive probe by the CeNTREX collaboration
[Quantum Sci. Technol., 6:044007, 2021] -- is calculated employing
highly-correlated relativistic many-body theory. Accounting for up to quintuple
excitations in the wavefunction expansion the final result is $W_T({\text{Tl)}}
= -6.25 \pm 0.31\, $[$10^{-13} {\langle\Sigma\rangle}_A$ a.u.] Interelectron
correlation effects on the tensor-pseudotensor interaction are studied for the
first time in a molecule, and a common framework for the calculation of such
effects in atoms and molecules is presented.
