Figure 2.

(a) Effective free energy profile of the porphycene molecule obtained from PIMD simulations at 290 K, projected on the δ₁ and δ₂ coordinates. The contour lines start at 0.75 k_BT and are separated by 1 k_BT. The x and o symbols mark the position of the trans and cis conformers, respectively, when optimized at the potential energy surface. We define “cis-like” conformations as those lying in the vicinity of (δ₁, δ₂) equal to (+0.4, +0.4) or (−0.4, −0.4). (b) Effective free energy projections along the q₁ (δ₁ = −δ₂) (solid lines) and q₂ (δ₁ = δ₂) (dashed lines) directions. Red and blue lines correspond to PIMD simulations at 290 and 100 K, respectively. (c) Nitrogen–nitrogen distance probability density obtained from PIMD simulations at 100 K (blue), PIMD simulations at 290 K (red), and MD simulation at 290 K (orange). Vertical lines indicate the minimum energy geometry values for the trans isomer (solid) and cis isomer (dashed).