Questions tagged [fcidump]

For questions about the FCIDUMP file format used for saving one and two electron integral.

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7 votes
1 answer
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Exploiting 8-fold symmetry of ERI tensor for building Coulomb and Exchange matrices

I'm trying to write a restricted Hartree Fock code in Fortran that reads in a file of zeroth-iteration 1 and 2 electron integrals (FCIDUMP format) and uses them to do the SCF procedure from an initial ...
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6 votes
1 answer
208 views

How to compute the overlap matrix in Python

I want to calculate the overlap integral (S), I made the code, but it is only worked when I use a basis function that describe 1s and when I include 2s orbital, I start to get error. The First Problem ...
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8 votes
0 answers
101 views

Interacting with pyscf integral library from Fortran [closed]

I would like to use libcint, the integral library in pyscf from Fortran. Its webpage has a Fortran API and developer manual, but ...
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6 votes
1 answer
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How to read data from an input and form two-electrons integral?

I am doing a code that can calculate the hartree-fock energy. I want to form the two-electrons integral by reading the data from the input like this one below. The first four number are the indices ...
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9 votes
1 answer
107 views

What do the parameters at the top of an FCIDUMP file mean?

A while ago I wrote a simple program that takes in an FCIDUMP file (generated by MOLRPO) and can determine matrix elements (or ...
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10 votes
1 answer
298 views

How to calculate FCI matrix elements from an FCIDUMP file

I'm interested in writing a simple program (as an exercise) that takes an FCIDUMP file (e.g. from a Molpro calculation) and can determine FCI matrix elements (e.g. to construct the entire FCI matrix ...
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7 votes
2 answers
241 views

What do the indices mean in an FCIDUMP file?

I generated an FCIDUMP file, which is copied below ...
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5 votes
2 answers
114 views

For software that does not support FCIDUMP format, what format is used and how can we get the software to interact with FCIDUMP integrals?

Complementary to this question: How do the various programs read or write integrals in FCIDUMP format? which attempts to list all electronic structure packages that support the ...
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8 votes
1 answer
244 views

How do the various programs read or write integrals in FCIDUMP format?

The FCIDUMP format was created by Peter Knowles and Nick Handy circa 1989 and now allows many electronic structure software packages to interact with each other. ...
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16 votes
1 answer
176 views

How are one-/two- particle reduced density matrices printed in mainstream programs?

The FCIDUMP format is widely used for the communication of one- and two- body integrals. I wonder what formats are used for 1-/2-RDMs, which are important in many basis rotation or compression tasks. ...
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