The excitation energy on EOM-CCSD QM/MM calculation?


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The EOMCCSD excitation energies are printed before printing the amplitudes.
Usually it looks like:


EOM-CCSD right-hand side iterations
--------------------------------------------------------------
Residuum Omega / hartree Omega / eV Cpu Wall
--------------------------------------------------------------

Iteration   1 using    1 trial vectors
0.3441834723226 0.4960382793046 13.49789 0.0 0.0

Iteration   2 using    2 trial vectors
0.0569282647087 0.4422999231339 12.03560 0.0 0.0


..... iterations

Iteration   7 using    7 trial vectors
0.0000000000000 0.4406555021952 11.99085 0.0 0.0
--------------------------------------------------------------
Iterations converged
largest EOMCCSD amplitudes: R1 and R2

Singles contributions
6a (alpha) --- 5a (alpha) -0.9481694324

Doubles contributions
6a (alpha) 7a (beta ) --- 3a (alpha) 5a (beta ) -0.1062858495
6a (alpha) 7a (beta ) --- 5a (alpha) 3a (beta ) -0.1323331866
7a (alpha) 6a (beta ) --- 3a (alpha) 5a (beta ) -0.1323331866
7a (alpha) 6a (beta ) --- 5a (alpha) 3a (beta ) -0.1062858495


The 0.4406555021952 11.99085 numbers from the last iteration give the EOMCCSD excitation energies in a.u. and in eV.

Best,
Karol