Scientia Sinica Chimica
Comparative study on the methodologies for calculating the excited state in DMRG
Jiajun Ren, Zhigang Shuai, He Ma
Abstract
Electronic excited state calculation consists of an important issue in theoretical and computational chemistry. Under the Pariser-Parr-Pople (PPP) model and taking polyacenes and polyenes as examples, we compared the accuracy and efficiency of the state specific method and the state average method for the excited state calculation in the density matrix renormalization group formalism. We found that the state specific method can correctly trace the low-lying excited states and can provide more accurate eigen energies than the state average method. Nevertheless, for higher-lying excited states, the state specific method could converge to wrong eigenstates, which should be highly cautioned.