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SUMMARY:A comparison of purification schemes for treating the idempotency
condition on the density matrix in electronic structure calculations
DTSTART;VALUE=DATE-TIME:20110714T114500Z
DTEND;VALUE=DATE-TIME:20110714T121500Z
DTSTAMP;VALUE=DATE-TIME:20231205T213231Z
UID:indico-contribution-5040@events.saip.org.za
DESCRIPTION:Speakers: Matthiam Hoffman (UFS)\nDuring the last 15 years the
re has been considerable interest in density matrix based methods for elec
tronic structure calculations. The “difficult” problem of ensuring ide
mpotency conservation of the density matrix through an appropriate purific
ation scheme as well as the use of the “nearsightedness” and associate
d sparsity of the density matrix to achieve linear scaling with system siz
e has been discussed by various authors. \n\nIn this study a density matri
x based fictitious electron dynamics method for calculating electronic str
ucture is used in a model nanoparticle calculation. This method uses an eq
uation of motion that implicitly ensures the idempotency constraint on the
density matrix. The effectiveness of this method compared to conventional
purification schemes is discussed. \n\nImportant properties of the densit
y matrix and its sub matrices\, including its sparsity and conditions for
effective linear independence of a column sub matrix of the density matrix
are discussed and illustrated within the context of this model system. It
is shown how the full density matrix can be reconstructed through a fast
QR factorization of a column sub matrix using a Choleski factorization of
its principal sub matrix.\n\nhttps://events.saip.org.za/event/7/contributi
ons/5040/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/5040/
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