  We study alchemical atomic energy partitioning as a method to estimate
atomisation energies from atomic contributions which are defined in physically
rigorous and general ways through use of the uniform electron gas as a joint
reference. We analyze quantitatively the relation between atomic energies and
their local environment using a dataset of 1325 organic molecules. The atomic
energies are transferable across various molecules, enabling the prediction of
atomisation energies with a mean absolute error of 20 kcal/mol - comparable to
simple statistical estimates but potentially more robust given their grounding
in the physics-based decomposition scheme. A comparative analysis with other
decomposition methods highlights its sensitivity to electrostatic variations,
underlining its potential as representation of the environment as well as in
studying processes like diffusion in solids characterized by significant
electrostatic shifts.
