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A hybrid technique of orthonormality constrained orbital optimization in SCF calculations
Author(s) -
PrasadBhattacharyya Sankar,
Mukherjee Debashis
Publication year - 1981
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/qua.560200603
Subject(s) - orthonormality , convergence (economics) , basis (linear algebra) , gradient descent , ab initio , set (abstract data type) , coupling (piping) , computer science , computational chemistry , mathematics , chemistry , physics , quantum mechanics , orthonormal basis , materials science , geometry , artificial intelligence , artificial neural network , metallurgy , programming language , economic growth , economics
A recently proposed orthonormality constrained orbital optimization technique is operationally modified further by coupling it to a gradient biased method, namely the steepest descent procedure of McWeeny. The hybrid technique developed in this way is shown to have better convergence properties in closed and unrestricted open‐shell calculations. The technique can be adapted to MCSCF procedures as well. The important role played by "orbital symmetries" in the operation of the method is analysed. Similarities and differences of the present method with the orthogonal gradient method are pointed out. Possible avenues of circumventing convergence difficulty that one may encounter in pathological cases, particularly in ab initio calculations involving extended basis set, are suggested.