table of contents
XTB(1) | XTB(1) |
NAME¶
xtb - performs semiempirical quantummechanical calculations, for version 6.0 and newer
SYNOPSIS¶
xtb [OPTIONS] FILE [OPTIONS]
DESCRIPTION¶
The xtb(1) program performs semiempirical quantummechanical calculations. The underlying effective Hamiltonian is derived from density functional tight binding (DFTB). This implementation of the xTB Hamiltonian is currently compatible with the zeroth, first and second level parametrisation for geometries, frequencies and non-covalent interactions (GFN) as well as with the ionisation potential and electron affinity (IPEA) parametrisation of the GFN1 Hamiltonian. The generalized born (GB) model with solvent accessable surface area (SASA) is also available available in this version. Ground state calculations for the simplified Tamm-Danceoff approximation (sTDA) with the vTB model are currently not implemented.
GEOMETRY INPUT¶
The wide variety of input formats for the geometry are supported by using the mctc-lib. Supported formats are:
For a full list visit: https://grimme-lab.github.io/mctc-lib/page/index.html
xtb(1) reads additionally .CHRG and .UHF files if present.
INPUT SOURCES¶
xtb(1) gets its information from different sources. The one with highest priority is the commandline with all allowed flags and arguments described below. The secondary source is the xcontrol(7) system, which can in principle use as many input files as wished. The xcontrol(7) system is the successor of the set-block as present in version 5.8.2 and earlier. This implementation of xtb(1) reads the xcontrol(7) from two of three possible sources, the local xcontrol file or the FILE used to specify the geometry and the global configuration file found in the XTBPATH.
OPTIONS¶
-c, --chrg INT
-u, --uhf INT
--gfn INT
--gfnff, --gff
--oniom METHOD LIST
--etemp REAL
--esp
--stm
-a, --acc REAL
--vparam FILE
--xparam FILE
--alpb SOLVENT [STATE]
-g, --gbsa SOLVENT [STATE]
--cma
--pop
--molden
--dipole
--wbo
--lmo
--fod
RUNTYPS¶
Note
You can only select one runtyp, only the first runtyp will be used from the program, use implemented composite runtyps to perform several operations at once.
--scc, --sp
--vip
--vea
--vipea
--vfukui
--vomega
--grad
-o, --opt [LEVEL]
--hess
--ohess [LEVEL]
--bhess [LEVEL]
--md
--metadyn [int]
--omd
--metaopt [LEVEL]
--path [FILE]
--reactor
--modef INT
GENERAL¶
-I, --input FILE
--namespace STRING
--[no]copy
--[no]restart
-P, --parallel INT
--define
--json
--citation
--license
-v, --verbose
-s, --silent
--ceasefiles
--strict
-h, --help
ENVIRONMENT VARIABLES¶
xtb(1) accesses a path-like variable to determine the location of its parameter files, you have to provide the XTBPATH variable in the same syntax as the system PATH variable. If this variable is not set, xtb(1) will try to generate the XTBPATH from the deprecated XTBHOME variable. In case the XTBHOME variable is not set it will be generated from the HOME variable. So in principle storing the parameter files in the users home directory is suffient but might lead to come cluttering.
Since the XTBHOME variable is deprecated with version 6.0 and newer xtb(1) will issue a warning if XTBHOME is not part of the XTBPATH since the XTBHOME variable is not used in production runs.
LOCAL FILES¶
xtb(1) accesses a number of local files in the current working directory and also writes some output in specific files. Note that not all input and output files allow the --namespace option.
INPUT¶
.CHRG
.UHF
mdrestart
pcharge
xcontrol
xtbrestart
OUTPUT¶
charges
wbo
energy
gradient
hessian
xtbopt.xyz, xtbopt.coord
xtbhess.coord
xtbopt.log
xtbsiman.log,xtb.trj.int
scoord.int
fod.cub
spindensity.cub
density.cub
molden.input
pcgrad
xtb_esp.cosmo
xtb_esp_profile.dat
vibspectrum
g98.out, g98l.out, g98_canmode.out, g98_locmode.out
.tmpxtbmodef
coordprot.0
xtblmoinfo
lmocent.coord
tmpxx
xtb_normalmodes, xtb_localmodes
TOUCH¶
xtbmdok
.xtbok
.sccnotconverged
WARNINGS¶
xtb(1) can generate the two types of warnings, the first warning section is printed immediately after the normal banner at startup, summing up the evaluation of all input sources (commandline, xcontrol, xtbrc). To check this warnings exclusively before running an expensive calculation a input check is implemented via the --define flag. Please, study this warnings carefully!
After xtb(1) has evaluated the all input sources it immediately enters the production mode. Severe errors will lead to an abnormal termination which is signalled by the printout to STDERR and a non-zero return value (usually 128). All non-fatal errors are summerized in the end of the calculation in one block, right bevor the timing analysis.
To aid the user to fix the problems generating these warnings a brief summary of each warning with its respective string representation in the output will be shown here:
ANCopt failed to converge the optimization
Hessian on incompletely optimized geometry!
EXIT STATUS¶
0
128
BUGS¶
please report all bugs with an example input, --copy dump of internal settings and the used geometry, as well as the --verbose output to xtb@thch.uni-bonn.de
RESOURCES¶
Main web site: http://grimme.uni-bonn.de/software/xtb
COPYING¶
Copyright (C) 2015-2018 S. Grimme. For non-commerical, academia use only.
10/05/2022 |