Unavailability of EOM-EA-CC(2,3) and doubt about EOM-EA-CCSDT method

Questions
#1

I was trying to use EOM-EA-CC(2,3) method which I checked is available in the manual but it gave me the same result as EOM-EA-CCSD. Because it only available with CCMAN only I make ccman2 false, and then I got this error

“DOING EOM-CC(2,3) CALCULATIONS
Doubles diagonal is not filtered.
EOM-EA: removing not attached states from the guess vector space
EOM(2,3) CPU 0.32 s wall 0.08 s
CCMAN JOB: ALL CPU 72.21 s wall 18.10 s”

I took input file from manual for testing and here it is
$molecule
0 1
H 0.774767 0.000000 0.458565
O 0.000000 0.000000 -0.114641
H -0.774767 0.000000 0.458565
$end

$rem
METHOD eom-cc(2,3)
BASIS 6-31G
EA_STATES [1,0,1,1]
ccman2 false
$end
Does anyone have any suggestions?

another point : There is no sign of EOM-EA-CCSDT method. Is this available in QChem 6.2.0.

#2

EOM-EA-CCSDT is available with “CCMAN2 = true” starting v6.2.2.

I do not yet have the answer for the EOMEA-CC(2,3) termination that you reported.

1 Like
#3

It seems EOM-EA-CC(2,3) is not implemented according to Table 7.2 (7.10.17 EOM-CC Job Control‣ 7.10 Coupled-Cluster Excited-State and Open-Shell Methods ‣ Chapter 7 Open-Shell and Excited-State Methods ‣ Q-Chem 6.2 User’s Manual). Hence the direct termination.

#4

Thanks Kaushik. I was confused with the note in section 7.10.23 “EOM-CC(2,3) works for EOM-EE, EOM-SF, and EOM-IP/EA. In EOM-IP, “triples” correspond to 3h2p excitations, and the computational scaling of EOM-IP-CC(2,3) is less.” May be it is a printing mistake. But again thanks for the clarification.