Chapter 2
Advanced Electronic Structure Theory
for High-Accuracy Prediction of Higher
Excited States and Its Application to
Photochromic Molecules
Takeshi Yanai
Abstract In this chapter, we describe our recent development of theoretical approach
to analyze photochemisty relevant electronic states (wave functions and energies)
for studying photochromic molecules with a promised numerical reliability. Our
approach is based on multireference (MR) theory, which is considered to be a critical
treatment to properly compute complex electronic structures arising in excited states.
It characterizes the wave function by explicitly expressing it as a correlated superposition of multiple electronic configurations (or Slater determinants). We mainly review
our recent development of extended multi-state complete active-space second-order
perturbation theory incorporated into density matrix renormalization group reference
wave functions. Its illustrative applications to molecular photochromic isomerizations, diarylethene derivatives and pentaarylbiimidazole are briefly reviewed in order
to show the applicability of our computational approach.
Keywords Multireference wave function theory · Density matrix renormalization
group · Extended multi-state complete active-space second-order perturbation
theory · Diarylethene
2.1 Introduction
In order to characterize the electronic excited states with computational methods, the
multireference (MR) treatment plays an essential role. It expresses the wave function
as a correlated superposition of multiple electronic configurations (or Slater determinants). In our recent work [29], we introduced an enhanced MR framework, referred
to as DMRG-XMS-CASPT2 (density matrix renormalization group extended multistate complete active-space second-order perturbation theory), that can accurately
compute complex electronic structures arising in excited states. This method was
T. Yanai (B)
Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho,
Chikusa-ku, Nagoya, Aichi 464-8602, Japan
e-mail: yanait@chem.nagoya-u.ac.jp
© Springer Nature Singapore Pte Ltd. 2020
H. Miyasaka et al. (eds.), Photosynergetic Responses in Molecules
and Molecular Aggregates, https://doi.org/10.1007/978-981-15-5451-3_2
29
Advanced Electronic Structure Theory
for High-Accuracy Prediction of Higher
Excited States and Its Application to
Photochromic Molecules
Takeshi Yanai
Abstract In this chapter, we describe our recent development of theoretical approach
to analyze photochemisty relevant electronic states (wave functions and energies)
for studying photochromic molecules with a promised numerical reliability. Our
approach is based on multireference (MR) theory, which is considered to be a critical
treatment to properly compute complex electronic structures arising in excited states.
It characterizes the wave function by explicitly expressing it as a correlated superposition of multiple electronic configurations (or Slater determinants). We mainly review
our recent development of extended multi-state complete active-space second-order
perturbation theory incorporated into density matrix renormalization group reference
wave functions. Its illustrative applications to molecular photochromic isomerizations, diarylethene derivatives and pentaarylbiimidazole are briefly reviewed in order
to show the applicability of our computational approach.
Keywords Multireference wave function theory · Density matrix renormalization
group · Extended multi-state complete active-space second-order perturbation
theory · Diarylethene
2.1 Introduction
In order to characterize the electronic excited states with computational methods, the
multireference (MR) treatment plays an essential role. It expresses the wave function
as a correlated superposition of multiple electronic configurations (or Slater determinants). In our recent work [29], we introduced an enhanced MR framework, referred
to as DMRG-XMS-CASPT2 (density matrix renormalization group extended multistate complete active-space second-order perturbation theory), that can accurately
compute complex electronic structures arising in excited states. This method was
T. Yanai (B)
Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho,
Chikusa-ku, Nagoya, Aichi 464-8602, Japan
e-mail: yanait@chem.nagoya-u.ac.jp
© Springer Nature Singapore Pte Ltd. 2020
H. Miyasaka et al. (eds.), Photosynergetic Responses in Molecules
and Molecular Aggregates, https://doi.org/10.1007/978-981-15-5451-3_2
29