Questions tagged [fcidump]

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

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PySCF: How to do CCSD calculations from an FCIDUMP file in HDF5 format?

Recently my question: Why does CCSD work, but not CCSD(T), after reading an FCIDUMP in PySCF? lead to a bug fix that allows users to do CCSD(T) calculations from an FCIDUMP file in PySCF. That was ...
Nike Dattani's user avatar
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2 votes
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PySCF: Two electron integrals, translate between aosym=s8 and full tensor

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alex math's user avatar
2 votes
1 answer
169 views

Why does CCSD work, but not CCSD(T), after reading an FCIDUMP in PySCF?

CCSD(T) works after an RHF calculation: Input: ...
Nike Dattani's user avatar
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2 votes
0 answers
326 views

How to read two electron integrals from pyscf

This is a follow-up question to this one I asked a few days ago. I in the meantime talked to my teacher and generate all the necessary integrals in PySCF. For the one electron integrals that isn't an ...
lela2011's user avatar
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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 ...
user avatar
6 votes
1 answer
841 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 ...
Abd-Elazeem Mohamed's user avatar
9 votes
0 answers
139 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 ...
Lancashire3000's user avatar
8 votes
1 answer
137 views

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 ...
Abd-Elazeem Mohamed's user avatar
8 votes
1 answer
151 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 ...
tmph's user avatar
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10 votes
1 answer
493 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 ...
tmph's user avatar
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9 votes
2 answers
503 views

What do the indices mean in an FCIDUMP file?

I generated an FCIDUMP file, which is copied below ...
fagd's user avatar
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5 votes
2 answers
188 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 ...
Nike Dattani's user avatar
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8 votes
1 answer
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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. ...
Nike Dattani's user avatar
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17 votes
1 answer
246 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. ...
Yingzhou Li's user avatar
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