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

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Posts 43
Hi everyone,

I performed EOM-CCSD QM/MM calculation for H2O molecules as a test case. My question is how to get the excitation energy? NWChem does not print it explicitly.

The following is the input file:
start e4h2o

memory total 4500 Mb

charge -1

basis spherical
* library 6-31++g** 
end

scf
thresh 1.0e-10
tol2e 1.0e-10
doublet
rohf
end

md
system e4h2o_opt
cutoff 1.0 qmmm 1.0
noshake solute
end

qmmm
mm_charges expand all
end

tce
freeze atomic core
ccsd
tilesize 8
attilesize 60
2eorb
2emet 14
diis 5
thresh 1.0d-5
nroots 2
eomsol 2
idiskx 1
end

task tce qmmm energy

The following is part of the output file, if you interested in the file, I can email it to you.
EOMCCSD root nr.                     1

Singles contributions
22a (alpha) --- 21a (alpha) 0.8957902018
25a (alpha) --- 21a (alpha) -0.1010208625
26a (alpha) --- 21a (alpha) 0.1495866218
27a (alpha) --- 21a (alpha) 0.2654077772
28a (alpha) --- 21a (alpha) -0.1891541423
34a (alpha) --- 21a (alpha) 0.1191698732

Doubles contributions
EOMCCSD root nr. 2

Singles contributions
22a (alpha) --- 21a (alpha) 0.1078353808
23a (alpha) --- 21a (alpha) 0.8192252691
24a (alpha) --- 21a (alpha) -0.2875936030
26a (alpha) --- 21a (alpha) -0.2268543499
27a (alpha) --- 21a (alpha) -0.3199715289
29a (alpha) --- 21a (alpha) 0.1373032935

Doubles contributions

Parallel integral file used     436 records with       0 large values

Bq nuclear interaction energy =   6.89703372905328     


QM/MM Energy


quantum energy                      -305.169313270 (-.801222E+06  kjoule/mol)
quantum energy adjusted -305.169313270 (-.801222E+06 kjoule/mol)
quantum energy internal -312.066346999 (-.819330E+06 kjoule/mol)
Bq-nuclear energy 6.897033729 (0.181082E+05 kjoule/mol)
Bq-electron energy 0.000000000 (0.000000E+00 kjoule/mol)
classical energy -4.752909506 (-.124788E+05 kjoule/mol)
total qmmm energy -309.922222776 (-.813701E+06 kjoule/mol)



Thanks in advance.

  • Karol Forum:Admin, Forum:Mod, NWChemDeveloper, bureaucrat, sysop
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Posts 35
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

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Threads 11
Posts 32
Quote:Wjb0920 Oct 28th 11:38 pm
Hi everyone,

I performed EOM-CCSD QM/MM calculation for H2O molecules as a test case. My question is how to get the excitation energy? NWChem does not print it explicitly.

The following is the input file:
start e4h2o

memory total 4500 Mb

charge -1

basis spherical
* library 6-31++g** 
end

scf
thresh 1.0e-10
tol2e 1.0e-10
doublet
rohf
end

md
system e4h2o_opt
cutoff 1.0 qmmm 1.0
noshake solute
end

qmmm
mm_charges expand all
end

tce
freeze atomic core
ccsd
tilesize 8
attilesize 60
2eorb
2emet 14
diis 5
thresh 1.0d-5
nroots 2
eomsol 2
idiskx 1
end

task tce qmmm energy

The following is part of the output file, if you interested in the file, I can email it to you.
EOMCCSD root nr.                     1

Singles contributions
22a (alpha) --- 21a (alpha) 0.8957902018
25a (alpha) --- 21a (alpha) -0.1010208625
26a (alpha) --- 21a (alpha) 0.1495866218
27a (alpha) --- 21a (alpha) 0.2654077772
28a (alpha) --- 21a (alpha) -0.1891541423
34a (alpha) --- 21a (alpha) 0.1191698732

Doubles contributions
EOMCCSD root nr. 2

Singles contributions
22a (alpha) --- 21a (alpha) 0.1078353808
23a (alpha) --- 21a (alpha) 0.8192252691
24a (alpha) --- 21a (alpha) -0.2875936030
26a (alpha) --- 21a (alpha) -0.2268543499
27a (alpha) --- 21a (alpha) -0.3199715289
29a (alpha) --- 21a (alpha) 0.1373032935

Doubles contributions

Parallel integral file used     436 records with       0 large values

Bq nuclear interaction energy =   6.89703372905328     


QM/MM Energy


quantum energy                      -305.169313270 (-.801222E+06  kjoule/mol)
quantum energy adjusted -305.169313270 (-.801222E+06 kjoule/mol)
quantum energy internal -312.066346999 (-.819330E+06 kjoule/mol)
Bq-nuclear energy 6.897033729 (0.181082E+05 kjoule/mol)
Bq-electron energy 0.000000000 (0.000000E+00 kjoule/mol)
classical energy -4.752909506 (-.124788E+05 kjoule/mol)
total qmmm energy -309.922222776 (-.813701E+06 kjoule/mol)



Thanks in advance.


If i am not mistaken I think you can only do EOM-CCSD for closed-shell systems.

Clicked A Few Times
Threads 12
Posts 43
Thanks
Thank you Karol for your instruction in reading output file.
Thank you Doudou, I will check my results.


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