EA/IP-EOM-CC Implemented in nwchem?

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Hello,

I have been looking into using EOM-CC for IP and EA of molecules and I do not really see a way to do it. (I have been doing Delta-SCF calculations in order to get IP and EA at the CCSDT level)

Has it been implemented into nwchem yet? Or is it still in the process of being put into the code?

Thanks,

-Cole

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There is some fairly new code to calculate IP and EA at the EOM-CCSD level at least. It doesn't appear to be officially documented yet.

If you are feeling adventurous, get the latest snapshot: http://www.nwchem-sw.org/download.php?f=Nwchem-dev.revision25890-src.2014-07-18.tar.gz

You will need to build NWChem with environment variables "IPCCSD=y" and "EACCSD=y" set to run these calculations.
Look at QA/tests/tce_eaccsd_ozone and QA/tests/tce_eaccsd_ozone for simple examples. They run fine on my laptop.

The source code is in src/tce/eaccsd/ and src/tce/ipccsd/ but is not especially rich in commentary.

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Quote:Mernst Aug 19th 7:17 pm
There is some fairly new code to calculate IP and EA at the EOM-CCSD level at least. It doesn't appear to be officially documented yet.

If you are feeling adventurous, get the latest snapshot: http://www.nwchem-sw.org/download.php?f=Nwchem-dev.revision25890-src.2014-07-18.tar.gz

You will need to build NWChem with environment variables "IPCCSD=y" and "EACCSD=y" set to run these calculations.
Look at QA/tests/tce_eaccsd_ozone and QA/tests/tce_eaccsd_ozone for simple examples. They run fine on my laptop.

The source code is in src/tce/eaccsd/ and src/tce/ipccsd/ but is not especially rich in commentary.


Hi,

I have attempted to compile this version of nwchem, but it seems to not work if USE_MPI is not set, and when I set USE_MPI="n" in environment variables, it fails to compile with this message:

checking whether a simple C MPI program compiles... no
configure: error: in `/home/cmjohns6/Nwchem-dev.revision25890-src.2014-07-18/src/tools/build':
configure: error: could not compile simple C MPI program
See `config.log' for more details
make[1]: *** [build/config.status] Error 1
make: *** [libraries] Error 1

I need to compile nwchem without MPI since my python script utilizes MPI to run in parallel many different nwchem calculations. Is this possible? I have defined the following environment variables when trying to compile:

export NWCHEM_TARGET=LINUX64
export ARMCI_NETWORK=SOCKETS
export LARGE_FILES=TRUE
export USE_NOFSCHECK=TRUE
export NWCHEM_MODULES=qm
export IPCCSD=y
export EACCSD=y

Thank you,
-Cole

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I don't remember exactly when the change came but I am pretty sure that NWChem requires MPI now. You can still just type in 'nwchem' without mpirun, and it behaves like before, but there is no valid build configuration for compiling without MPI support.

I'm sure that you are not eager to change well-established processes just to get a couple new capabilities, but I think you will have to do it at some point. If you are already comfortable with Python, perhaps Fabric with the possible addition of SSHFS would let you get away from your current MPI based scripts? http://www.fabfile.org

Or you could even keep your current work flow and binaries for most jobs, but compile a separate nwchem 6.3 installed in its own directory for experimenting with EA-CCSD and IP-CCSD. Just add a 'nwchem63' wrapper script to set up the environment with the right binary and libraries prior to execution; for a few experiments the non-compatibility with your Python-MPI flow should be tolerable. Then if it the capability is really useful you can contemplate making bigger workflow changes.

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EA/IP-EOMCCSD implementation
The EA/IP-EOMCCSD functionalities will be available in the 6.5 NWChem release (a week from now).
In order to enable these methods in you binaries please set the following variables prior the compilation:
export EACCSD=y
export IPCCSD=y

I am also attaching two examples of the EA/IP-EOMCCSD inputs (more details will be available in the 6.5 manual).



      1. EA-EOMCCSD ###

start tce_eaccsd_ozone

title "tce_eaccsd_ozone"

echo

memory stack 1000 mb heap 200 mb global 500 mb

geometry units bohr
symmetry c1
O 0.0000000000 0.0000000000 0.0000000000
O 0.0000000000 -2.0473224350 -1.2595211660
O 0.0000000000 2.0473224350 -1.2595211660
end

basis spherical
* library cc-pvdz
END

scf
thresh 1.0e-10
tol2e 1.0e-10
singlet
rhf
end

tce
eaccsd
nroots 2
freeze atomic
tilesize 20
thresh 1.0d-6
end

task tce energy


      1. IP-EOMCCSD ###

start tce_ipccsd_f2

title "tce_ipccsd_f2"

echo

memory stack 1000 mb heap 200 mb global 500 mb

geometry units angstroms
symmetry c1
F    0.0000000000        0.0000000000   0.7059650
F 0.0000000000 0.0000000000 -0.7059650
end

basis spherical
* library cc-pvdz
end

scf
thresh 1.0e-10
tol2e 1.0e-10
singlet
rhf
end

tce
ipccsd
nroots 1
freeze atomic
thresh 1.0e-7
end

task tce energy



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