Questions tagged [full-configuration-interaction]

For questions about FCI (full configuration interaction) calculations.

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6 votes
2 answers
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What are the limitations of FCI?

I am aware of the fact that Full Configuration Interaction scales poorly. Taking into account that the number of $n$-times excited Slater determinants of an $N$-particle System with $M$ basis ...
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11 votes
2 answers
308 views

FCI without Hartree-Fock

Recently, I came across some lecture notes on electronic structure theory which had something peculiar about it. I noticed that FCI (configuration interaction) was introduced before Hartree-Fock ...
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7 votes
3 answers
355 views

Open source FCI solvers for exact diagonalization of the many-electron Hamiltonian

What open source solvers (according to the generally accepted Open Source Definition i.e. licensed under a valid open source license) are available for full configuration interaction calculations? ...
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8 votes
3 answers
396 views

What are the advantages of the Davidson diagonalization method over other sparse matrix diagonalization methods?

I am interested to understand the advantages of the Davidson diagonalization method over other sparse matrix diagonalization routines. For instance, Intel MKL.
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6 votes
2 answers
478 views

Analytic Hessian at the level of full CI?

This is a follow-up question to my previous question: Computing analytic derivatives of molecular Hamiltonians obtained from solving Hartree-Fock equations. After looking at various quantum chemistry ...
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8 votes
1 answer
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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
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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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14 votes
1 answer
302 views

Orbitals in full CI and DFT with true functional

Is there any paper that proves/disproves that the occupied orbitals obtained using full Configuration Interaction (CI) are the same as the orbitals obtained using DFT (assuming we use the exact ...
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28 votes
1 answer
525 views

How accurate are the most accurate calculations?

Taking into account the fact that the theory of quantum gravity does not exist and the QED calculations are not possible for most realistic chemical systems, what levels of accuracy can we expect from ...
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