The input of the main program

To run the MCTDH-X program, it is best to have each calculation done in a separate directory. The program needs two files to perform the computation. First, the dynamic library, libmctdhx.so, and second, the input file with computational/numerical parameters MCTDHX.inp. The library contains the above four subroutines that define the Hamiltonian and the initial state (Get_Initial_Coefficients.F, Get_Initial_Orbitals.F, Get_InterParticle_Potential.F,
[4]Get_1bodyPotential.F). If any of these files was modified, the library has to be re-compiled and copied to the computation's directory! Recompiling the library libmctdhx.so is conveniently achieved by issueing the command:

 libmake

After compilation, the library can be copied to the working directory by typing

 libcp

Finally, the input files should be copied to the working directory. This can be done by typing

 inpcp .

The two files MCTDHX.inp and analysis.inp are now inside the working directory. The details of the input variables in those files can be taken from the in-line documentation in the input file or the html code documentation. The MCTDHX.inp file basically contains variables like the particle number, the number of orbitals, the (dimensionless) interaction strength, number of primitive basis functions, their type, details of the integration (integrator,stepsize,accuracy,order,...), and many more. See table 3 for all currently available parameters in the main program and their meaning.

Table 3: MCTDH-X main program input file parameters.

System Parameters Namelist
Parameter	Meaning	Options
JOB_TYPE	Select problem, i.e. MCTDH for bosons, MCTDH for fermions or TDCI for bosons.	Character, `BOS', `FER', `FCI'; Default `BOS'
Morb	Select number of time-dependent, variationally optimized basis functions	Integer, no default.
Npar	Select number of structureless particles	Integer, no default.
xlambda_0	Adjust prefactor of two-body potential in the Hamiltonian	Real, no default.
mass	Mass of the particles	Real, default 1.d0
Job_Prefactor	Select which direction to propagate the equations of motion in time.	Complex, (0.0d0,-1.0d0) Forward propagation; (0.0d0,+1.0d0) Backward propagation, (-1.0d0,0.0d0) (Improved) Relaxation; Default (-1.d0,0.d0).
NProjections	Number of times that the projection operator $\hat{\mathcal{P}}$ is applied to the right-hand side of the orbital equations of motion	Integer, default $2$.
GUESS	Specifying if the initial guess is defined in .dat files, the routines Get_Initial_Orbitals.F, Get_Initial_Coefficients.F, or in the binary files CiC_bin and Psi_bin	Character, `HAND' means the Get_Initial... routines are used, `DATA' means .dat files will be read in, `BINR' means *_bin files will be read in, default `HAND' .
Diagonalize_OneBodyh	Select to use eigenfunctions of the one-body potential in Get_1bodyPotential.F	Logical, .T. or .F., .T. only non-FFT1-DVRs2, i.e., DVR_X/Y/Z$\neq$4, default is .F.
Binary_Start_Time	Define point in time at which the wavefunction is read from binary files in the case of GUESS=`BINR'	Real, no default.
Restart_State	If restarting from a Block Davidson computation, this selects which state in the block is used as the initial value.	Integer, default 1
Restart_Orbital_FileName	Define filename of orbitals to read if GUESS=`DATA'	Character, no default.
Restart_Coefficients_FileName	Define filename of coefficients to read if GUESS=`DATA'	Character, no default.
Vortex_Seeding	In propagations: Multiply initial orbitals with phase/density profile?	Logical, default .F.
Vortex_Imprint	In relaxations: Apply a projection operator to a certain orbital density profile?	Logical, default .F.
Profile	If Vortex_Imprint is true, this will select the respective shape of the imprinted (select 'tanh','poly','phase', or 'phase-x' or define custom profile in Get_Vortex_Profile.F in /source/ini_guess_pot/)	Character, default 'tanh'
Fixed_LZ	Multiply fixed phase profile on the orbital in relaxations	Logical, default .F.
OrbLz	How many times $2\pi$ the phase is going to jump if Fixed_LZ is true. If any value is -666, the respective orbital is unchanged.	Integer, default 0,0,0,0,0,0,0,0,0,0
DVR Namelist
DIM_MCTDH	Specifying the dimensionality of the problem	Integer, 1,2 or 3, default 1.
NDVR_X	Specifying the number of DVR functions in X dimension	Integer, default 256.
NDVR_Y	Specifying the number of DVR functions in Y dimension	Integer, default 1.
NDVR_Z	Specifying the number of DVR functions in Z dimension	Integer, default 1.
DVR_X	Which DVR will be used in X direction	Integer, 1 means harmonic oscillator DVR, 3 means sine DVR, 4 means FFT DVR and 5 exponential DVR, default 4.
DVR_Y	Which DVR will be used in Y direction	Integer, 1 means harmonic oscillator DVR, 3 means sine DVR, 4 means FFT DVR and 5 exponential DVR, default 4.
DVR_Z	Which DVR will be used in Z direction	Integer, 1 means harmonic oscillator DVR, 3 means sine DVR, 4 means FFT DVR and 5 exponential DVR, default 4.
x_initial	Where the spatial grid in X dimension starts	Real, default $-8.0$.
x_final	Where the spatial grid in x dimension stops	Real, default $8.0$.
y_initial	Where the spatial grid in Y dimension starts	Real, default $-8.0$.
y_final	Where the spatial grid in Y dimension stops	Real, default $8.0$.
z_initial	Where the spatial grid in Z dimension starts	Real, default $-8.0$.
z_final	Where the spatial grid in Z dimension stops	Real, default $8.0$.
Integration Namelist
Time_Begin	Time at which the simulation shall start	Real, default $0.0$.
Time_Final	Time at which the simulation shall stop	Real, default $20.0$.
Time_Max	Maximal time	Real, default $1.d99$.
Output_TimeStep	Times at which orbital output shall be written.	Real, default $0.1$.
Output_Coefficients	Multiple of Output_TimeStep at which coefficient output shall be written	Real, default $1$
Integration_Stepsize	Stepsize of the integration scheme (for relaxation this is fixed, for propagation this is adaptive)	Real, default $0.01$
Error_Tolerance	Error tolerance for the integration scheme	Real, default $1.d-9$
Minimal_Occupation	Minimal occupation for not considering an eigenvalue as 0 in the inversion of the density matrix elements	Real, default $1.d-12$
Minimal_Krylov	Minimal size of Krylov basis for coefficients' integration	Integer, default $4$
Maximal_Krylov	Maximal size of Krylov basis for coefficients' integration	Integer, default $20$
Orbital_Integrator	Integrator for the orbital equations of motion	Character, `ABM' or `OMPABM' means that (OpenMP parallelized) Adams Bashforth Moulton predictor corrector integrator is used, `BS' means Bullirsch-Stör, `RK' means Runge-Kutta, and `STIFF' means ZVODE specialized to stiff equations is used; default `OMPABM'.
Orbital_Integrator_Order	Order of the integration of the orbitals' integrator, choice depends on the Integrator	Integer, for `RK' it is 5 or 8, for `ABM'/`OMPABM' it is 2 to 8, for `BS' its 2 to 16, and for `STIFF' it is 1 or 2, default $7$.
Orbital_Integrator_MaximalStep	Restricts the maximum stepsize in the orbital equations' integration	Real, default $0.01$.
Write_ASCII	Specifying wether ASCII files are output during the computation	Logical, default .T..
Error_Rescale_TD	Specifying a scale for the Error_Tolerance parameter for time-dependent one-body potentials.	Real, default $1.0$.
LZ	Trigger one-body angular momentum operator in the Hamiltonian	Logical, .T. or .F., default .F. .
OMEGAZ	Prefactor of one-body angular momentum operator.	Real, default $0.0$.
STATE	Which eigenstate of the Hamiltonian to compute.	Integer, 1 means the groundstate, default $1$. Stable for Coefficients_Integrator=`DSL' or `DAV' .
Coefficients_Integrator	Which integrator to use for the coefficients equations of motion.	Character, `MCS' means MCTDH SIL routine, `DSL' means MCTDH SIL diagonalization routine, `DAV' means Davidson diagonalization, `BDV' means block Davidson diagonalization; no default.
BlockSize	If Block Davidson (BDV) is used as integrator for the coefficients then this selects the number of coefficient vectors in the block	Integer, default 4
Olsen	If Block Davidson is used as integrator for the coefficients, this flag toggles the Olsen correction (Jacobi-Davidson)	Logical, default .F.
RLX_Emin	If Block Davidson is used as integrator for the coefficients then this selects the lower energy bound for the block	Real, default -1.d90
RLX_Emax	If Block Davidson is used as integrator for the coefficients then this selects the upper energy bound for the block	Real, default 1.d90
Potential Namelist
whichpot	Select from predefined list of potentials, see table 20.	Character, no default.
parameter1	Parameters to tune predefined potentials, see table 20.	Real, default $1.0$.
parameter2-30	Parameters to tune predefined potentials, see table 20.	Real, default $0.0$.
Interaction Namelist
Which_Interaction	Select predefined interparticle interaction potentials	Character, default `gauss'; For time-dependent interactions, `TDHIM', 'TDgauss1' a Gaussian sinusoidially modulated amplitude, and 'TDgauss2', a Gaussian with sinusoidially modulated width, are currently defined.
Interaction_Width	Modify parameter in the interparticle interaction.	Real, default $0.15$.
interaction_parameter1-10	Parameters to tune predefined interaction potentials, see table B.	Real, default $0.0$.
Interaction_Type	How the Local interaction potentials $\hat{W}_{sl}$ and their action is evaluated	Integer, 0 means $\delta$-like contact interaction potential, 1 to 4 will use the routine Get_InterParticle_Potential.F to generate the interaction potential. 1 means the potential is separable and hence one potential vector is allocated for each spatial dimension; 2 means the potential depends on the distance of the particles only, hence, a tridiagonal representation is used (only for aequidistant DVRs 3,4 and 5); 3 means full interaction matrix will be stored (very large array!!!), 4 interaction matrix evaluated with successive FFT (IMEST); 5 means time-dependent interaction with IMEST; 6 means time-dependent contact interaction; 7 means both contact and non-zero ranged interactions with IMEST; default 0.