Two intermediates in VDENS require contractions of four-virtual Γ elements:

I(ia) += Γ(ab,cd)*<ib||cd>
I(ab) += Γ(ae,cd)*<be||cd>

Also, for UHF, evaluating the S² expectation value requires Γ(ab,cd).

<α+|S²|β> = SAMP(pq)*D(pq) + SAMP(pqrs)*D(pqrs)

Instead of storing Γ(ab,cd) a direct algorithm is used to evaluate a number of distributions of Γ(ab,cd) and use them immediately.

Γ(ab,cd) = τ(ij,ab)*λ(cd,ij)

HF/AUG-CC-PVTZ/C2v on crisp

	Γ(abcd) stored	Γ(abcd) direct
Wallclock time	30.04 s	52.96 s
System time	6.43 s	3.04 s
GAMLAM size	72,613,888 B	7,340,032 B

H2/AUG-CC-PVQZ/D2h on crisp

	Γ(abcd) stored	Γ(abcd) direct
Wallclock time	76.60 s	29.03 s
System time	12.70 s	4.71 s
GAMLAM size	146,800,640 B	1,572,864 B