Photosynthesis is by far the most important process in transforming energy from solar radiation into chemical energy for life on Earth.Electronic-vibrational coupling plays an important role in the photosynthetic systems.We employed quantum chemistry calculations and molecular dynamics simulations to calculate the electronic-vibrational coupling in the excited states of photosynthetic reaction center of purple bacteria Rhodobacter sphaeroides.The ground and lowest excited (Qy) states of isolated bacteriochlorophyll a (BChla) and bacteriopheophytin (BPhe) molecules were first optimized using time-dependent density functional theory (TDDFT).Normal mode analyses were then performed to calculate the Huang-Rhys factors of the intramolecular vibrational modes.