A Systematic Evaluation of Large Language Models for PTSD Severity Estimation: The Role of Contextual Knowledge and Modeling Strategies. - Panagiotis Kaliosis; Adithya V. Ganesan; Oscar N. E. Kjell; Whitney Ringwald; Scott Feltman; Melissa A. Carr; Dimitris Samaras; Camilo Ruggero; Benjamin J. Luft; Roman Kotov; H. Andrew Schwartz (CoRR, 2026)