3. An even α, ω-disubstituted [n]cumulene (3) where the current density flows circularly around the carbon atoms. The length of 3 is challenging to reach synthetically, but is chosen to emphasize the circular current density. Before we consider our three molecular systems, it is important to first understand the basic AOs and their gradients that serve as foundational elements of the current density. Therefore, we illustrate the orbitals and gradients of Equation 24 using a 1s-and 1p-orbital in Figure . These two atomic orbitals constitute the simplest building blocks of the more complex MOs that we will look at later. The x-, y-, and z-components of the gradient of a 1s-orbital are displayed in the top row, whilst the analogous components of a 1px-orbital are depicted in the row beneath. The last column shows the resulting vector field, F(x, y, z), which is calculated as F(x, y, z) = ∇ψ where ψ is either an s-, a px-or a pz-orbital. Of note is the substantial gradients across the nodal planes (see F(x, y, z) of the px-or pz-orbital), which, as we will demonstrate later, play a key role in the path of the current density through molecules.