In summary, this work provides a quantitative study of the ground and excited electronic states of the carbon clusters focusing particularly on ablation applications. We use the Guassian16 Software Package to compute the ground state thermochemistry and excited electronic states. We perform a geometry optimization of the excited electronic states of molecules of interest during ablation. Following this, the effects of excited electronic states on the partition function and hence the thermodynamic properties are studied. Finally, the equilibrium compositions for various mixtures are studied using the state-of-the-art databases and the databases developed in this paper. A major take away of this paper is the large difference in heats of formation obtained from the state of the art thermodynamic tables and the new ab-initio data computed in this paper. Another im-portant highlight is the errors encountered in the thermodynamics upon neglecting the effects of low lying electronic states at these high temperatures. The differences amount up to 11%. Further, it is found that C 4 and C 4 H have electronic transitions with large oscillator strengths in the VUV region. The optimized geometry of excited electronic state of interest of C 4 ( 3 Σ - u ) has a linear structure whereas the excited electronic state of C 4 H has a bent geometry. Finally, comparison of the equilibrium mole fractions using the new ab-initio data versus state-of-the-art high temperature thermodynamic tables show significant deviations from each other. These differences are up to an order of magnitude for the C 4 molecule and are solely attributed to the large differences in the heats of formation. The paper also emphasizes the need to include the liner triplet and rhombic singlet isomers of C 4 in calculations since addition of the rhombic isomer increased the total equilibrium mole fraction of the C 4 molecule by 28%.