UNO DMRG CAS CI calculations of binuclear manganese complex Mn(IV)2O2(NHCHCO2)4: Scope and applicability of Heisenberg model

• Published in: Journal of computational chemistry 2019-01, Vol.40 (2), p.333-341
• Main Authors: Kawakami, Takashi, Miyagawa, Koichi, Sharma, Sandeep, Saito, Toru, Shoji, Mitsuo, Yamada, Satoru, Yamanaka, Shusuke, Okumura, Mitsutaka, Nakajima, Takahito, Yamaguchi, Kizashi
• Format: Article
• Language: English
• Subjects: active orbital selection; Antiferromagnetism; binuclear manganese complex; CaMn4O5 cluster; DMRG CAS; Exchanging; Heisenberg theory; magnetic interaction; Manganese; Polarization (spin alignment); Statistical models
• ISSN: 0192-8651; 1096-987X
• DOI: 10.1002/jcc.25602

Both direct exchange and super‐exchange interactions cooperate to realize inter‐spin magnetic interaction in binuclear manganese complex Mn(IV)2O2(NHCHCO2)4 with a di‐μ‐oxo path. We revisited this spin system using DMRG CAS methods and CAS selection procedures. Our results indicate that our previous “dynamically extended spin polarization” (DE‐SP) procedure for organic polyradicals and so forth does not work well. Thus, we have examined another selection procedure, the “dynamically extended super‐exchange” (DE‐SE) procedure. DMRG CASCI [18,18] by UB3LYP(HS)‐UNO(DE‐SE) can realize antiferromagnetic J values similar to experimental ones (−87 cm−1). In addition, all J values between all spin states (HS[septet],IS[quintet],IS[triplet],LS[singlet])were also shown to be correct under sufficiently large M values. © 2018 Wiley Periodicals, Inc. Both direct exchange and super‐exchange interactions cooperate to realize inter‐spin magnetic interaction in binuclear manganese complex Mn(IV)2O2(NHCHCO2)4 with di‐μ‐oxo path. The authors revisit this spin system using DMRG CAS methods and CAS selection procedures.