Abstract
<jats:p> The character of electronically excited states, such as the balance between local excitation (LE), charge transfer (CT), and the spatial separation of electron and hole densities, strongly influences absorption properties and the electronic-state landscape at the Franck–Condon geometry of organic chromophores, evaluated at ground-state nuclear configurations. Conventional analyses based on single equilibrium geometries neglect thermal fluctuations that can significantly alter this character. We present ExFiT, a GPU-accelerated ensemble based computational pipeline for fingerprinting excited-state character across temperatures. ExFiT combines finite-temperature Wigner sampling with ensemble-resolved excited-state analysis and principal component analysis to quantify distributions of CT metrics, electron-hole separation, entanglement, and orbital participation. Application to representative chromophores ( <jats:italic toggle="yes">trans</jats:italic> -Azobenzene, ( <jats:italic toggle="yes">E</jats:italic> )-Hemithioindigo, <jats:italic toggle="yes">para</jats:italic> -Nitroaniline, and Coumarin 481) reveals distinct regimes of thermal behavior, ranging from robust excited-state character to broadened descriptor distributions and temperature-dependent bright-state reordering within the Franck–Condon ensemble. These results demonstrate how thermal fluctuations modulate excited-state electronic structure and establish the applicability of ExFiT as a framework for generating statistically meaningful initial-condition ensembles for spectral simulations and future nonadiabatic dynamics studies. </jats:p>