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Second‐order shakeup terms in electron propagator calculations on F 2 and H 2 O 2
Author(s) -
Ortiz J. V.
Publication year - 1998
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/(sici)1097-461x(1998)69:2<175::aid-qua5>3.0.co;2-s
Subject(s) - propagator , electron , order (exchange) , computational chemistry , chemistry , physics , atomic physics , quantum mechanics , finance , economics
A new approximation of the electron propagator includes second‐order terms in the superoperator Hamiltonian matrix that are not present in the nondiagonal, renormalized method (NR2) of J. Chem. Phys. 108 , 1008 (1998). These terms are not difficult to calculate and resemble expressions obtained with various propagator and coupled‐cluster formalisms. Their inclusion produces larger, more accurate vertical ionization energies of F 2 and H 2 O 2 . Cancellations between the second‐order terms considered here and the first‐order terms present in the NR2 method reduce the importance of shakeup operators in describing the first few cationic states of these molecules. Dyson orbitals for 2 A final states of H 2 O 2 exhibit qualitatively important mixings between canonical orbitals. © 1998 John Wiley & Sons, Inc. Int J Quant Chem 69: 175–182, 1998