# Tag Info

15

The solutions to the Schrödinger equation are not unique in general, and uniqueness depends on several things such as the form of the potential and boundary conditions. Many papers have discussed uniqueness of solutions to the Schrödinger equation for specific classes of potentials and boundary conditions, but in general it is possible to come up with cases ...

15

It is hard to claim that any FCI code overcomes the exponential wall, especially for strongly correlated systems. There are many algorithms, e.g. CDFCI, HCI, FCIQMC, ACI, etc., which significantly reduce the computational cost of direct FCI calculations and represent wavefunctions by sparse vectors. However, in my opinion, all of them only reduce the ...

10

One way of determining this is using the projected density of states (P-DOS) This resolves the DOS into specific orbitals thereby allowing you to discretize each orbitals weight for a specific energy. $\mathrm{PDOS}_\nu(E) = \sum_i \psi^*_{i,\nu} [\mathbf S | \psi_{i}\rangle]_\nu D(E-\epsilon_i)$ Note here that $|\psi_i\rangle$ is the $i$th eigenvector and ...

9

I have yet to find a source that lays this out explicitly, but from the examples I could find, it is not too hard to infer the meaning of these sections. To start with (and possibly point you in the right direction to look for more information), this type of *.wfn file was developed as the input format for AIMPAC and quickly spread to be used as an output ...

8

Not all determinants contribute significant correlation, especially configurations for excitations of multiple electrons to higher energy orbitals, which is the basis for CAS methods; i.e. only choose the “important” orbitals in which to perform FCI. Doing so works acceptably for weakly correlated systems, but since FCI is still performed within the active ...

5

As you mention, your graphene hamiltonian operates on sites, i.e. it is a lattice model. Its solution therefore does not provide a wave function in real space, it provides wave function amplitudes on the graphene lattice. That said, given the amplitudes on the graphene lattice, you can create an approximate real-space wave function from an eigenstate of the ...

3

Different people will have slightly different opinions, so take my answer with a grain of salt. I'll try to give the minimum publishable basis sets, i.e. if you use worse basis sets than these, you'll have a strong reason why you do so, written in the article, otherwise you'll probably face suspicion from the reviewers. DFT (excluding double hybrid) geometry ...

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