@@ -31,7 +31,7 @@ If we recognize that we have one of these equations for every combination of
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* i* and * a* spin-orbitals, then this equation may be viewed as a matrix
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eigenvalue problem:
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- <img src =" ./figures/matrix-eigenvalue-problem.png " height =" 30 " >
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+ <img src =" ./figures/matrix-eigenvalue-problem.png " height =" 25 " >
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To solve this equation, we need an expression for the matrix elements in terms
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of things we already know, i.e. Fock matrix elements and two-electron
@@ -76,7 +76,9 @@ possible determinants arising from this configuration,
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are components of one singlet and one triplet in the following combinations:
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- <img src =" ./figures/singlet-triplet-combinations.png " height =" 60 " >
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+ <img src =" ./figures/triplet-combinations.png " height =" 60 " >
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+
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+ <img src =" ./figures/singlet-combinations.png " height =" 60 " >
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where the superscript is the spin multiplicity (* 2S+1* ) and the subscript is
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the * M<sub >S</sub >* value of the wave function. So, if we wanted to compute
@@ -89,10 +91,10 @@ wanted only triplets, we could require that the <html>α</html> and
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Let's begin with the singlets. Starting from the spin-orbital eigenvalue
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expression and the equation for the CIS Hamiltonian matrix elements in the
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- previous section, we may write a spin-factored equation for the
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- < html > & alpha ; </ html > coefficients as
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+ previous section, we may write a spin-factored equation for the < html > & alpha ; </ html >
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+ coefficients as
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- <img src =" ./figures/spin-factored-eqn.png " height =" 30 " >
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+ <img src =" ./figures/spin-factored-eqn.png " height =" 60 " >
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Note that the mix-spin cases (where * j=* <html >&alpha ; </html > and
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* b=* <html >&beta ; </html > or * vice versa* ) do not contribute since the Fock
@@ -157,7 +159,7 @@ The definition of the ***A*** matrix is just the CIS matrix itself, *viz.*
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while ** X** and ** Y** are the parameters of single excitations and
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de-excitations, respectively, and the *** B*** matrix is simply
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- <img src =" ./figures/B-matrix.png " height =" 30 " >
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+ <img src =" ./figures/B-matrix.png " height =" 25 " >
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Thus, the row/column dimension of the TDHF/RPA Hamiltonian is twice that of the
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CIS Hamiltonian, and the matrix is non-symmetric (so you must be careful about
@@ -174,28 +176,28 @@ Hamiltonian storage cost), one can rearrange the eigenvalue equations. First
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write eigenvalue equation two separate equations, each in terms of the
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submatrices ** A** and ** B** :
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- <img src =" ./figures/smarter-tdhf-1.png " height =" 30 " >
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+ <img src =" ./figures/smarter-tdhf-1.png " height =" 25 " >
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and
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- <img src =" ./figures/smarter-tdhf-2.png " height =" 30 " >
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+ <img src =" ./figures/smarter-tdhf-2.png " height =" 25 " >
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Now take +/- combinations of these equations to obtain
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- <img src =" ./figures/smarter-tdhf-3.png " height =" 30 " >
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+ <img src =" ./figures/smarter-tdhf-3.png " height =" 25 " >
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and
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- <img src =" ./figures/smarter-tdhf-4.png " height =" 30 " >
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+ <img src =" ./figures/smarter-tdhf-4.png " height =" 25 " >
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Solve for *** (X+Y)*** in the second equation:
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- <img src =" ./figures/smarter-tdhf-5.png " height =" 30 " >
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+ <img src =" ./figures/smarter-tdhf-5.png " height =" 25 " >
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Insert this result into the first equation, rearrange a bit, and finally
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obtain:
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- <img src =" ./figures/smarter-tdhf-6.png " height =" 30 " >
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+ <img src =" ./figures/smarter-tdhf-6.png " height =" 25 " >
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This is an eigenvalue equation of the same dimension as the CIS eigenvalue
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equation (number of occupied orbitals times number of unoccupied orbitals),
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