Initializations of Wavefunctions

External quantum chemistry and DFT codes (Gaussian, GAMESS, and pySCF)

You can use external quantum chemistry and DFT codes such as Gaussian, GAMESS, and pySCF to generate a trail wavefunction. Please refer to the TurboGenius tutorial [https://github.com/kousuke-nakano/turbotutorials].

Built-in DFT code (prep.x)

In this section, we describe the INPUT file that controls DFT calculation. The input file is built using Fortran namelists. Keywords are divided into different sections according to their meanings.

Simulation section

The sections and the main parameters are listed and shortly described in the following. Keywords that are not required can be omitted in the input file: they will assume a default value.

Simulation section

Parameter	Datatype	Default	Description
itest4	NA	NA	itest4 = -4: Standard DFT run. itest4 = -8: DFT calculation with twice larger basis for the Hartree potential.
iopt	NA	NA	iopt = 1: Initialize with no potential (no Hartree, xc, correlation). iopt = 0: Continuation, starting from wavefunctions read from fort.10_new and occupation read from occupationlevels.dat (both generated after iopt = 1 run). iopt = 2: Same as iopt = 0, but write main matrices (basis set/Hamiltonian overlaps, charge/spin density).

Pseudo section

Pseudo section (summary)

Parameter	Datatype	Default	Description
nintpsa	NA	NA	Number of integer points for pseudopotential if present.
pseudorandom	NA	NA	Use a random integration mesh for pseudo with the algorithm for QMC by R. Fahy.
npsamax	NA	NA	Multiplication factor for the number of pseudo integration points. Note that, use npsmax > 2 if the code terminates with the error ‘Increase npsamax’.

Optimization section

Optimization section

Parameter	Datatype	Default	Description
molopt	NA	NA	Do not change this value, as DFT works with molecular orbitals only.

Readio section

Readio section

parameter name	datatype	default	description
writescratch	NA	NA	writescratch = 0: Writes binary scratch files on disk to speed up continuation and allow non-self-consistent calculations and post-processing tools. The following files are written: tmp000xxx: One for each processor. These files contain basis/Hamiltonian overlap matrix elements in the first record. In the second record, they contain charge/spin density distributed matrices. total_densities.sav: A single file containing the total (i.e., not distributed over the real space integration grid) charge density in the first record and the total spin density in the second record (in the case of LSDA calculations). wavefunction.sav: A single file containing the final Kohn-Sham eigenvectors for all the bands. If k-points are present, each record contains the eigenvectors for a single k-point in the order as they appear in the occupationlevels.dat file. writescratch = 1: Does not write any scratch file on disk. Continuing from previous runs and non-self-consistent calculations will not be possible.

Parameters section

Parameters section

Parameter	Datatype	Default	Description
decoupled_run	NA	NA	If .true. the code starts a k-independent calculation. When k-points are activated, this option allows performing an independent self-consistent cycle for each k-point without performing the k-points average of electronic density. To be used before a twist average calculation in QMC.
yes_kpoints	NA	NA	Set it to .true. if you plan to do a calculation with k-points sampling. In this case, the phase of the wavefunction fort.10 is disregarded.
epsbas	NA	NA	Real space cutoff for the periodic basis set (keyword PBC_C in the first record of the wave function fort.10). Note that, if DFT energy is different from what is expected, then try decreasing the cutoff.

Molecule section

Molecule section

parameter name	datatype	default	description
nx	NA	NA	Number of lattice points for the real space integration grid in the x direction. By default, nx = ny = nz
ax	NA	NA	Space (a.u.) for an open system in the x direction; for periodic systems, it is chosen as the cell parameter in the same direction and need not be specified. By default, ax = ay = az
nbufd	NA	NA	Input value for the buffer dimension. Note that, in the complex code, the buffer dimension is automatically doubled. In this case, consider decreasing the buffer dimension if you have a memory problem.

Kpoints section

Kpoints section

parameter name	datatype	default	description
kp_type	NA	NA	This integer specifies the type of k-points which will be chosen in the calculation. kp_type = 0: Do not perform any k-points sampling and use the phase specified in the fort.10 as the unique k-point. kp_type = 1: Use the Monkhorst-Pack algorithm to generate equally-spaced k-points in the first Brillouin zone. The size of the grid in the three Cartesian directions is determined by the integers nk1, nk2, nk3. Note that nk1 must be set to a value > 0. If nk2, nk3 are not set, then they are taken to be equal to nk1. Also, if skip_equivalence (see below) is set to .false. the number of k-points might be reduced. In this case, run the tool find_kpoints.x with the desired input in order to know how many processors must be allocated. kp_type = 2: When this is used, k-points are set by the user and their number is specified by the integer nk1. In this case, the section KPOINTS is needed (see below). kp_type = 3: Generates k-points path along high-symmetry lines in the first Brillouin zone. The initial and final points of these segments are specified in the section KPOINTS (see below). The number of extremal points is specified by the integer nk1 and the number of points in each segment is specified by the integer nk2. kp_type = 4: Generate k-points randomly within the first Brillouin zone. The number of k-points is specified by nk1. KPOINTS section is not needed.
nk1, nk2, nk3	NA	NA	Meanings depend on the value of kp_type, see above for a detailed explanation.
k1, k2, k3	NA	NA	For kp_type = 1, set k1, k2, k3 equal to 1 in order to apply an offset to the k-point grid generated by the Monkhorst-Pack algorithm. In some cases, this can help to reach

Additional information:

• Monkhorst-Pack mesh:

  &kpoints
  kp_type=1
  nk1=4
  nk2=4
  nk3=4
  skip_equivalence=.false.
  double_kpgrid=.true.
  

• User-defined k-points are written in the following manner. wkp(i) denotes the weight corresponding to the kpoint xkp(:,i) if the total weight is different from one.:

  wkp(i) is the weight corresponding to the the kpoint xkp(:,i).
  ! NB: if the total weight is different from on
  ! xkp(1,1) xkp(2,1) xkp(3,1) wkp(1)
  ! xkp(1,2) xkp(2,2) xkp(3,2) wkp(2)
  ! ......
  KPOINTS
  0.1667 0.1667 0.5000  0.5
  0.5000 0.5000 0.5000  0.5
  # blank line and after k-points for spin down electrons
  -0.1667 -0.1667 -0.5000  0.5
  -0.5000 -0.5000 -0.5000  0.5
  

DFT section

Parameter List

Parameter Name	Datatype	Default	Description
contracted_on	NA	NA	If .true. it acts on the contracted basis (considerably faster).
maxit	NA	NA	Maximum number of iterations in the self-consistent cycle.
epsdft	NA	NA	Tolerance in the convergence of total energy.
typeopt	NA	NA	typeopt = 0: Use self consistency method with standard mixing. typeopt = 2: Linear mixing scheme. typeopt = 3: Conjugate gradients method with SR acceleration. typeopt = 4: Anderson mixing scheme with Jacobian acceleration, no use of mixing is made; this method looks to be the faster and therefore the preferred among the available ones. For information on the algorithm see doc/tex/parbcs.tex, Ch. V
mixing	NA	NA	Choose a small value for better convergence. If even in this way it does not converge, switch on the smearing technique setting optocc=1 (suggested for open shell systems). Alternatively you can change iteration method with typeopt=3 (conjugate gradients) which will certainly converge for mixing small enough. In these cases mixing means just the maximum amplitude in the step.
mixingder (abbr)	NA	NA	Case 1 (typeopt = 3): Used to evaluate numerically the first and second derivatives. Case 2 (typeopt = 4): Used to be closer to the linear regime for the evaluation of the Jacobian (mixingder << 1).
tfcut	NA	NA	Used only with typeopt = 0/2/4. It is used for preconditioning to improve convergence of small q charge fluctuations. Suggested value of tfcut = \frac{1}{{xi_{TF}}^2} where xi is the Thomas-Fermi length expressed in a.u.
orthodiag	NA	NA	.false. the Kohn-Sham eigenvectors are not orthogonalized after each Hamiltonian diagonalization.
maxold	NA	NA	The number of previous iterations to be considered in the numerical evaluation of Jacobian with typeopt = 4.
typedft	NA	NA	typedft = 0: DFT calculation with Hartree potential only. typedft = 1: LDA (PZ 1981). typedft = 2: LDA (OB 1994). typedft = -1,-2: Same as the two above, but with the corresponding fit performed by imposing continuity in the correlation energy at rs = 1. typedft = 3: KZK finite volume DFT: should be more accurate for finite volume. typedft = -3: Different fitting procedure, suitable for open systems. Could be used with periodic systems too, but it is less stable. typedft = 4: Standard LSDA. typedft = -4: Standard LSDA, but with the corresponding fit performed by imposing continuity in the correlation energy at rs = 1. typedft = 5: LSDA + KZK (not applied on spin) (typedft = -5 similar to typedft = -3).
weightvh	NA	NA	Weight of the hartree potential. Setting weightvh \neq 1 is used just for testing.
weightxc	NA	NA	Weight of the exchange energy. When weightxc = 0 no exchange and when weightcorr = 1 standard LDA is used.
weightcorr	NA	NA	Weight of the correlation energy, e.g. weightcorr = 0 no correlation, weightcorr = 1 standard LDA.
optocc	NA	NA	optocc = 0: Use standard occupation of levels. It works well only for closed shell systems (insulators or special cases). Occupations are read from standard input (see below); the number of occupations read is chosen by the parameter nelocc (neloccdo for down spin electrons) which must be specified in input. In this case we have occupations(1:nelocc) = 2 for LDA; occupations(1:nelocc) = 1 && occupationdo(1:neloccdo) = 1 for LSDA. optocc = 1: Use a smeared Fermi distribution with a spread given by the parameter epsshell (see below). In this case: occupations(i) = \exp{ \frac{eig(i)-ef}{epsshell}+1} where the Fermi energy ef is determined by the constraint, sum(occupations(1:bands)) = no. of electrons via bisection method . For LSDA (|typedft| = 4, 5) two Fermi distributions are introduced for up and down electrons. In the case of k-points sampling, the Fermi energy is determined by averaging over ef computed for each k-point.
epsshell	NA	NA	Spread of the Fermi distribution used when optocc = 1. The unit is Ha.
memlarge	NA	NA	Optimize speed at the cost of much greater memory requirements. The whole basis set is saved on disk!
epsover	NA	NA	Minimum tolerance for the lowest eigenvalues of the overlap matrix. If epsover < 0 no orthogonalization is implemented (faster but less stable).
mincond	NA	NA	Disregard the first mincond-1 direction regardless of the condition number limited by epsover. This is useful to have better cancellation errors as a function e.g. of pressure.
maxcg	NA	NA	With typeopt = 3 (conjugate gradient) each maxcg steps restart the conj. grad. procedure. If maxcg = 0 no restarting is performed (discouraged since numerically unstable).
bands	NA	NA	The number of lowest eigenvalues of Khon-Sham equations to be evaluated. By default bands = nelup + 7 where nelup is the number of spin up electrons. This corresponds to assuming at most an 8-fold degenerancy in the last occupied shell.
nelocc	NA	NA	If nelocc > 0, it is the number of occupations that are read in the last record of the input file. Occupation values can only be (0,2] (paired orbitals), -1 (unpaired at the end) or 0 (unoccupied). If nxs \times nys \times nzs > 0 this record is just after the ones to read the input magnetization (see below).
neloccdo	NA	NA	It is similar to nelocc but for the spin down electrons which are assumed with no unpaired orbitals. Another record with neloccdo integers be written below. Note that, in this case occupations for up spin can take values 1 (occupied paired orbital), -1 (unpaired), 0 (unoccupied orbital). Instead occupations for down spin electrons can take values 1 (occupied paired orbital) and 0 (unoccupied orbital).
randspin	NA	NA	Used for initializing magnetization. If randspin > 0, add random component to the orbitals. If randspin < 0 initialize with maximum possible spin given density and grid (see below). If zero no action.
jaccond	NA	NA	Minimum threshold for the condition matrix in the self-consistent approach typeopt = 4.
nxs nys nzs	NA	NA	Dimension of the grid where the magnetization is defined along the x, y, z direction. The format is written below.
h_field	NA	NA	If h\_field > (<) 0 put a magnetic field increasing (decreasing) the magnetization with the staggering given by the table sxyz defined for randspin.
optimize_overs	NA	NA	If .true. optimize the overlap matrices calculation if the phase for spin down electrons is equal or opposite to the phase for up spin electrons. Otherwise it is automatically set to .false..
write_den	NA	NA	If .true. write the overlap matrix elements for effective Hamiltonian calculations to the disk.
zero_jas	NA	NA	If .true. set the one-body Jastrow to zero at the end of the DFT calculation.
fix_density	NA	NA	If the flag decoupled_run is set to .true. (&parameters card) as well as the yes_kpoints flag (&kpoints card), the k-points are evolved independently but using the averaged electronic density.

Additional information:

• nxs nys nzs

  Dimension of the grid where the magnetization is defined along the x, y, z direction: The format is

  !  After "/" or "occupation list"
  ! # empty line
  ! s111 s211 s311 ... snxs11
  ! s121 s221 s321 ... snxs11
  ! s1nys1 ... ... ... snxsnys1
  ! # empty line
  ! s112 s212 s312 ... snxs12
  ! ...
  ! # empty line
  ! s11nzs s21nzs s31nzs ... snxs1nzs
  ! ...
  ! s1nysnzs ... ... ... snxsnysnzs