# ABINIT, aim input variables:

## List and description.

This document lists and provides the description of the name (keywords) of the "aim" input variables to be used in the input file for the AIM(Bader) executable of the ABINIT package.

##### Copyright (C) 1998-2017 ABINIT group (DCA,XG,RC,YG,FJ)

### Content of the file : alphabetical list of "aim" variables.

A. atom atrad
B.
C. coff1 coff2 crit
D. denout dltyp dpclim
E.
F. foldep follow folstp
G. gpsurf
H.
I. inpt irho ivol
J.
K.
L. lapout lgrad2 lgrad lstep2 lstep
M. maxatd maxcpd
N. ngrid nphi nsa nsb nsc ntheta
O.
P. phimax phimin
Q.
R. radstp ratmin rsurdir rsurf
S. scal surf
T. thetamax thetamin
U.
V. vpts

atom
Mnemonics: index of ATOM
Executable: aim
Mentioned in topic: Bader.
Very frequently used: [5/5] in aim tests, [0/0] in tuto aim tests. Test list: {v3:[57],v4:[31,33,34],v6:[19]}.
Variable type: integer
Default is 1

Index of the investigated atom.

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atrad
Mnemonics: bader ATomic RADius
Executable: aim
Mentioned in topic: Bader.
Moderately used: [2/5] in aim tests, [0/0] in tuto aim tests. Test list: {v3:[57],v6:[19]}.
Variable type: real
Default is 1.0

A first estimation of the Bader radius (not too important - it is used only two times)

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coff1
Mnemonics: COeFFicient 1
Executable: aim
Mentioned in topic: Bader.
Rarely used: [0/5] in aim tests, [0/0] in tuto aim tests.
Variable type: real
Default is 0.98

See the input variable ratmin@aim.

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coff2
Mnemonics: COeFFicient 2
Executable: aim
Mentioned in topic: Bader.
Rarely used: [0/5] in aim tests, [0/0] in tuto aim tests.
Variable type: real
Default is 0.95

See the input variable ratmin@aim.

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crit
Mnemonics: computation of CRITical points
Executable: aim
Mentioned in topic: Bader.
Very frequently used: [5/5] in aim tests, [0/0] in tuto aim tests. Test list: {v3:[57],v4:[31,33,34],v6:[19]}.
Variable type: integer
Default is 0

Drives the computation of critical points.

- [0] not
- [-1] reading from the file ``root''.crit
- [1] calculated (simplified version)
- [2] calculated (standard version - recommended)
- [3] calculated (the original version)

The original version searches all critical points (CPs) starting from the center between two and three atoms (atom - neighbor(s)) by Newton-Raphson algorithm - without tests (not recommended) - don't use together with surface analysis !

The simplified and standard versions search CP(3,-1) starting from the center of the pairs~atom-neighbor; then CP(3,1) from the center between two CP(3,-1) and finally CP(3,3) from the center between two CP(3,1). The robust Popeliers's algorithm is used. The difference between the two is based in the fact that the standard version makes the test if the CP is really on the Bader surface of the calculated atom for each CP, while the simplified version does this only for CP(3,-1). When CP analysis is rather fast (with respect to surface determination), 2 is recommended. In all cases the number of neighbors considered is limited by distance cutoff (variable maxatd@aim)

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denout
Mnemonics: electronic DENsity OUTput
Executable: aim
Mentioned in topic: Bader.
Rarely used: [0/5] in aim tests, [0/0] in tuto aim tests.
Variable type: integer
Default is 0

Output of the electronic density. The specification of the line (plane) in the real space must be given in the input variable vpts@aim and grid in ngrid@aim. It is also possible to get only the valence density or the core density (see dltyp@aim).

- 0, no output
- 1, 1D distribution
- 2, 2D distribution

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dltyp
Mnemonics: Density or Laplacian TYP output
Executable: aim
Mentioned in topic: Bader.
Rarely used: [0/5] in aim tests, [0/0] in tuto aim tests.
Variable type: integer
Default is 0

Specification of the contribution of the electronic density corresponding to the density and/or laplacian output (see denout@aim and lapout@aim)

- 0, total electronic density
- 1, only the valence density
- 2, only the core density

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dpclim
Mnemonics: DPCLIM
Executable: aim
Mentioned in topic: Bader.
Moderately used: [1/5] in aim tests, [0/0] in tuto aim tests. Test list: {v4:[33]}.
Variable type: real
Default is 1.d-2

If two "numerically different" critical points are separated by less than dpclim, they are considered to be the same critical point. This often happens because of numerical inaccuracies : one CP might be "seen" by two different finite elements. The default should be OK when the ecut is quite large, on the order of 60 Hartree. For less accurate calculations of the density, increase the default value to 5.d-2, let's say.

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foldep
Mnemonics: FOLlow DEParture
Executable: aim
Mentioned in topic: Bader.
Rarely used: [0/5] in aim tests, [0/0] in tuto aim tests.
Variable type: real(3)
Default is 3*0.0

Needed in the case follow=1 only. Defines the starting point.

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follow
Mnemonics: FOLLOW the gradient path
Executable: aim
Mentioned in topic: Bader.
Rarely used: [0/5] in aim tests, [0/0] in tuto aim tests.
Variable type: integer
Default is 0

Follow the gradient path to the corresponding atom starting from the position specified in the input variable foldep.

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folstp
Mnemonics: FOLlow STeP
Executable: aim
Mentioned in topic: Bader.
Rarely used: [0/5] in aim tests, [0/0] in tuto aim tests.
Variable type: real
Default is 0.5

The first step for following the gradient path.

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gpsurf
Mnemonics: GraPhic output for the bader SURFace
Executable: aim
Mentioned in topic: Bader.
Very frequently used: [5/5] in aim tests, [0/0] in tuto aim tests. Test list: {v3:[57],v4:[31,33,34],v6:[19]}.
Variable type: integer
Default is 0

Drives the graphic output (gnuplot script) of the irreducible part of the calculated Bader surface.

- 0, not output
- 1, output

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inpt
Mnemonics: numer of INtegration PoinTs
Executable: aim
Mentioned in topic: Bader.
Very frequently used: [5/5] in aim tests, [0/0] in tuto aim tests. Test list: {v3:[57],v4:[31,33,34],v6:[19]}.
Variable type: integer
Default is 100

Number of radial points used for integration of the Bader charge (not too sensitive).

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irho
Mnemonics: Integration of the charge density RHO
Executable: aim
Mentioned in topic: Bader.
Very frequently used: [5/5] in aim tests, [0/0] in tuto aim tests. Test list: {v3:[57],v4:[31,33,34],v6:[19]}.
Variable type: integer
Default is 0

Drives the integration of the charge of the Bader atom.

- 0, not calculated
- 1, calculated (usual mode)

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ivol
Mnemonics: Integration of the VOLume
Executable: aim
Mentioned in topic: Bader.
Moderately used: [1/5] in aim tests, [0/0] in tuto aim tests. Test list: {v6:[19]}.
Variable type: integer
Default is 0

Drives the integration of the volume of the Bader atom.

- 0, not calculated
- 1, calculated

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lapout
Mnemonics: electronic density LAPlacian OUTput
Executable: aim
Mentioned in topic: Bader.
Rarely used: [0/5] in aim tests, [0/0] in tuto aim tests.
Variable type: integer
Default is 0

Output of the laplacian of electronic density. The specification of the line (plane) in the real space must be given in the input variable vpts and grid in ngrid. It is also possible to get only the valence density or the core density (see dltyp).

- 0, no output
- 1, 1D distribution
- 2, 2D distribution

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lgrad2
Mnemonics: Low GRADient criterion 2
Executable: aim
Mentioned in topic: Bader.
Rarely used: [0/5] in aim tests, [0/0] in tuto aim tests.
Variable type: real
Default is 1.d-5

Determines the criterion for deciding that a CP has been found. See lgrad for more details.

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lgrad
Mnemonics: Low GRADient criterion
Executable: aim
Mentioned in topic: Bader.
Very frequently used: [3/5] in aim tests, [0/0] in tuto aim tests. Test list: {v3:[57],v4:[33,34]}.
Variable type: real
Default is 1.d-12

The search for one particular CP is decided to be successful when either the norm of the gradient of the electron density is smaller than lgrad or when the length of the planned search step is smaller than lstep. If the number of search step becomes larger than an internal limit (presently set to 100), one will allow a weaker criteria for satisfaction, based on lgrad2 and lstep2. If the internal limit is reached, and the criteria on lgrad2 and lstep2 are not satisfied, then the searching procedure continues with the next seed.

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lstep2
Mnemonics: Length of the planned search STEP 2
Executable: aim
Mentioned in topic: Bader.
Rarely used: [0/5] in aim tests, [0/0] in tuto aim tests.
Variable type: real
Default is 1.d-5

Determines the criterion for deciding that a CP has been found. See lgrad for more details.

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lstep
Mnemonics: Length of the planned search STEP
Executable: aim
Mentioned in topic: Bader.
Very frequently used: [3/5] in aim tests, [0/0] in tuto aim tests. Test list: {v3:[57],v4:[33,34]}.
Variable type: real
Default is 1.d-10

Determines the criterion for deciding a CP has been found. See lgrad for more details.

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maxatd
Mnemonics: MAXimal ATomic Distance
Executable: aim
Mentioned in topic: Bader.
Very frequently used: [5/5] in aim tests, [0/0] in tuto aim tests. Test list: {v3:[57],v4:[31,33,34],v6:[19]}.
Variable type: real
Default is 10.0

Atoms within this maximal distance are considered in order to start the search of a CP.

Note that the supercell, determined by nsa, nsb, and nsc might be too small to actually lead to the consideration of all the desired atoms.

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maxcpd
Mnemonics: MAXimal CP Distance
Executable: aim
Mentioned in topic: Bader.
Very frequently used: [4/5] in aim tests, [0/0] in tuto aim tests. Test list: {v3:[57],v4:[33,34],v6:[19]}.
Variable type: real
Default is 5.0

The CPs are searched for within this maximal distance.

Note that the supercell, determined by nsa, nsb, and nsc might be too small to actually lead to the consideration of all the critical points.

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ngrid
Mnemonics: Number of GRID points
Executable: aim
Mentioned in topic: Bader.
Rarely used: [0/5] in aim tests, [0/0] in tuto aim tests.
Variable type: integer(2)
Default is 2*30

Defines the grid in real space, for the density and laplacian outputs, governed by denout and lapout.

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nphi
Mnemonics: Number of PHI angle
Executable: aim
Mentioned in topic: Bader.
Very frequently used: [5/5] in aim tests, [0/0] in tuto aim tests. Test list: {v3:[57],v4:[31,33,34],v6:[19]}.
Variable type: integer
Default is 48

With ntheta, this variable defines the angular grid for the integration within the Bader volume, in particular, the number of phi angles, to be used between phimin and phimax. When the difference between these two variables is 2 pi, the recommended value of nphi is 48. When it is pi (for symmetry reasons), the recommended value is 32. When it is pi/2 (for symmetry reasons), the recommended value is 20.

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nsa
Mnemonics: Number of Supercell points in direction A
Executable: aim
Mentioned in topic: Bader.
Rarely used: [0/5] in aim tests, [0/0] in tuto aim tests.
Variable type: integer
Default is 3

These variables define a "supercell", from the primitive cell repeated along each primitive direction. This supercell is build as follows :

      do isa=-nsa,nsa
       do isb=-nsb,nsb
        do isc=-nsc,nsc
          -> here, the cell is translated by the vector
          -> (isa,isb,isc) in crystallographic coordinates
          -> and accumulated, to give the supercell
        enddo
       enddo
      enddo

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nsb
Mnemonics: Number of Supercell points in direction B
Executable: aim
Mentioned in topic: Bader.
Rarely used: [0/5] in aim tests, [0/0] in tuto aim tests.
Variable type: integer
Default is 3

These variables define a "supercell", from the primitive cell repeated along each primitive direction. This supercell is build as follows :

      do isa=-nsa,nsa
       do isb=-nsb,nsb
        do isc=-nsc,nsc
          -> here, the cell is translated by the vector
          -> (isa,isb,isc) in crystallographic coordinates
          -> and accumulated, to give the supercell
        enddo
       enddo
      enddo

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nsc
Mnemonics: Number of Supercell points in direction C
Executable: aim
Mentioned in topic: Bader.
Rarely used: [0/5] in aim tests, [0/0] in tuto aim tests.
Variable type: integer
Default is 3

These variables define a "supercell", from the primitive cell repeated along each primitive direction. This supercell is build as follows :

      do isa=-nsa,nsa
       do isb=-nsb,nsb
        do isc=-nsc,nsc
          -> here, the cell is translated by the vector
          -> (isa,isb,isc) in crystallographic coordinates
          -> and accumulated, to give the supercell
        enddo
       enddo
      enddo

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ntheta
Mnemonics: Number of THETA angles
Executable: aim
Mentioned in topic: Bader.
Very frequently used: [5/5] in aim tests, [0/0] in tuto aim tests. Test list: {v3:[57],v4:[31,33,34],v6:[19]}.
Variable type: integer
Default is 32

With nphi, this variable defines the angular grid for the integration within the Bader volume, in particular, the number of theta angles, to be used between thetamin and thetamax. When the difference between these two variables is pi, the recommended value of ntheta is 32. When it is pi/2 (for symmetry reasons), the recommended value is 20.

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phimax
Mnemonics: PHI MAXimal angle
Executable: aim
Mentioned in topic: Bader.
Very frequently used: [4/5] in aim tests, [0/0] in tuto aim tests. Test list: {v3:[57],v4:[31,33,34]}.
Variable type: real
Default is 2.0

Angular limits of integration of the Bader volume for the phi variables. The number of integration points is given by nphi. The range of integration can be decreased if there are symmetry reasons for doing this.

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phimin
Mnemonics: PHI MINimal angle
Executable: aim
Mentioned in topic: Bader.
Rarely used: [0/5] in aim tests, [0/0] in tuto aim tests.
Variable type: real
Default is 0.0

Angular limits of integration of the Bader volume for the phi variables. The number of integration points is given by nphi. The range of integration can be decreased if there are symmetry reasons for doing this.

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radstp
Mnemonics: RADial STeP
Executable: aim
Mentioned in topic: Bader.
Moderately used: [2/5] in aim tests, [0/0] in tuto aim tests. Test list: {v3:[57],v6:[19]}.
Variable type: real
Default is 0.05

The length of the first step in the search of the exact Bader radius.

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ratmin
Mnemonics: Radius Atomic MINimal
Executable: aim
Mentioned in topic: Bader.
Moderately used: [2/5] in aim tests, [0/0] in tuto aim tests. Test list: {v3:[57],v6:[19]}.
Variable type: real
Default is 1.0

The first estimation of the smallest radius of the basin of the atom (the distance at which the procedure that follows the gradient path announces that the gradient path finishes in the corresponding atom) This parameter is very important for the speed of the calculation, but this first estimation is not usually used because the program makes a new one based on the knowledge of CPs. In fact after the CP analysis, the new estimation is done by the product of the ad hoc parameter coff1 (default 0.98) by the distance of the nearest bonding CP. If there is a problem later, coff2 (default 0.95) is used instead.

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rsurdir
Mnemonics: Radius SURface DIRection
Executable: aim
Mentioned in topic: Bader.
Rarely used: [0/5] in aim tests, [0/0] in tuto aim tests.
Variable type: real(2)
Default is 2*0.0

In the case rsurf=1, gives the direction (angular coordinates theta,phi) along which the radius of the Bader surface is to be determined.

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rsurf
Mnemonics: computation of the Radius bader SURFace
Executable: aim
Mentioned in topic: Bader.
Rarely used: [0/5] in aim tests, [0/0] in tuto aim tests.
Variable type: integer
Default is 0

Drive the computation of the radius of the Bader surface for the angles specified in the input variable rsurdir

- 0, not calculated
- 1, calculated

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scal
Mnemonics: SCALing of the cartesian coordinates
Executable: aim
Mentioned in topic: Bader.
Rarely used: [0/5] in aim tests, [0/0] in tuto aim tests.
Variable type: real(3)
Default is 1.0 1.0 1.0

SCALing of the cartesian coordinates.

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surf
Mnemonics: computation of the bader SURFace
Executable: aim
Mentioned in topic: Bader.
Very frequently used: [5/5] in aim tests, [0/0] in tuto aim tests. Test list: {v3:[57],v4:[31,33,34],v6:[19]}.
Variable type: integer
Default is 0

Drive the computation of the full Bader surface.

- 0, not calculated
- 1, calculated

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thetamax
Mnemonics: THETA MAXimal angle
Executable: aim
Mentioned in topic: Bader.
Very frequently used: [4/5] in aim tests, [0/0] in tuto aim tests. Test list: {v3:[57],v4:[31,33,34]}.
Variable type: real
Default is pi

Angular limits of integration of the Bader volume for the theta variables. The number of integration points is given by ntheta. The range of integration can be decreased if there are symmetry reasons for doing this.

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thetamin
Mnemonics: THETA MINimal angle
Executable: aim
Mentioned in topic: Bader.
Rarely used: [0/5] in aim tests, [0/0] in tuto aim tests.
Variable type: real
Default is 0.0

Angular limits of integration of the Bader volume for the theta variables. The number of integration points is given by ntheta. The range of integration can be decreased if there are symmetry reasons for doing this.

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vpts
Mnemonics: Vectors defining the PoinTS of the surface
Executable: aim
Mentioned in topic: Bader.
Rarely used: [0/5] in aim tests, [0/0] in tuto aim tests.
Variable type: real(6) (Comment: 6 for 1D, 9 for 2D)
Default is 6*0.0

Basic vectors of the line or rectangle in real space, defining the points for which the density or laplacian will be computed, thanks to denout or lapout

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