Single Point Energy

Overview

A single point (SP) calculation evaluates a fixed molecular geometry without moving any atoms. MAPLE always reports the parsed coordinates, charge/multiplicity metadata, and electronic energy; verbose=1 adds per-atom gradients.

This is the simplest and fastest task type available in MAPLE, making it the foundation upon which more complex workflows are built.

Usage

The single point task is invoked by including the #sp header command in the input file. No method or convergence parameters are used because there is no iterative procedure.

#sp

Use the optional verbose parameter when you need gradients. MAPLE accepts only verbose=0 and verbose=1; verbose=2 is rejected, and the older spelling verbosity is not valid for SP jobs.

Input Example

Checked-in MAPLE example: examples/sp/sp3.inp. It requests verbose=1 so the output includes charge/multiplicity, energy, and gradients.

#model=ANI-2x
#sp(verbose=1)

C       0.65365800      1.02013500      0.25040200
C      -0.95129600     -1.02931400      0.57474200
C       1.95888600     -0.93622000      0.00515500
N       0.79077500     -0.14946600     -0.38846900
N      -0.42242100      1.80163100      0.01564100
O      -1.87211100     -0.71447900     -0.39360600
H      -1.49152400     -0.99165700     -1.23718800
H       1.93501500      1.43895500     -0.76274600
H       1.14080200      1.20947000      1.20910000
H      -1.06000700      1.56870100     -0.72483100
H      -0.64277300      2.56184400      0.62878400
H      -1.22475800     -0.59467400      1.53295400
H      -0.61313000     -2.06366600      0.60833500
H       1.61854500     -1.95264400      0.20633800
H       2.67877500     -0.97401900     -0.81539800
H       2.47397200     -0.55869000      0.89670300

Run it from the MAPLE source tree with maple examples/sp/sp3.inp. The same example has a D4 variant at examples/sp/sp3_d4.inp.

Parameters

The single point task accepts the following parameter:

Output

The output file from a single point calculation always contains parsed coordinates, charge/multiplicity metadata, and the total energy in Hartree (Eh). Gradients depend on verbose:

• verbose=0 -- parsed coordinates, charge/multiplicity, and energy.
• verbose=1 -- verbose=0 output plus per-atom gradients in Hartree/Angstrom.

Complete example output from examples/sp/sp3.out:

**********************************************************************
*                                                                    *
*                        M   A   P   L   E                           *
*                                                                    *
*      MAchine-learning Potential for Landscape Exploration          *
*                                                                    *
*                                                                    *
*      © 2025 University of Pittsburgh. All rights reserved.         *
*      Licensed under CC BY 4.0 for academic use.                    *
*                                                                    *
*      Principal Developer:  Xujian Wang                             *
*                                                                    *
**********************************************************************


Parsing # commands...
Global parameter: model = ANI-2x
Task set to 'sp'
Parsed configuration:
----------------------------------------
Task: sp
model          : ani2x
verbose        : 1

                             Coordinates
**********************************************************************

Group 1 (inline)
--------------------
1    C              0.653658             1.020135             0.250402
2    C             -0.951296            -1.029314             0.574742
3    C              1.958886            -0.936220             0.005155
4    N              0.790775            -0.149466            -0.388469
5    N             -0.422421             1.801631             0.015641
6    O             -1.872111            -0.714479            -0.393606
7    H             -1.491524            -0.991657            -1.237188
8    H              1.935015             1.438955            -0.762746
9    H              1.140802             1.209470             1.209100
10   H             -1.060007             1.568701            -0.724831
11   H             -0.642773             2.561844             0.628784
12   H             -1.224758            -0.594674             1.532954
13   H             -0.613130            -2.063666             0.608335
14   H              1.618545            -1.952644             0.206338
15   H              2.678775            -0.974019            -0.815398
16   H              2.473972            -0.558690             0.896703

Charge: 0, Multiplicity: 1
Energy: -304.7642932897 Hartree

Gradients (Hartree/Angstrom):
  Gradient = -Force
  Atom  El        Gx              Gy              Gz
  1    C      -0.10266493      0.02860843      0.11792911
  2    C      -0.08336351     -0.02371526      0.04541698
  3    C       0.03426485     -0.01383988      0.00515845
  4    N       0.10547175      0.05071949     -0.09252290
  5    N       0.00947110     -0.01377346      0.00264503
  6    O       0.02184403      0.00224924     -0.00525583
  7    H      -0.00991479     -0.00544633      0.00266360
  8    H       0.03686071     -0.03305264     -0.05529496
  9    H      -0.01167883     -0.00082533     -0.01351971
  10   H       0.00696653      0.00887080     -0.00033596
  11   H       0.00424815     -0.00923034     -0.00473377
  12   H      -0.00369785     -0.00480554      0.00827175
  13   H       0.00377101      0.00490504     -0.00487071
  14   H      -0.00491144      0.00881686     -0.00243353
  15   H      -0.00285685      0.00055546      0.00761027
  16   H      -0.00380990     -0.00003653     -0.01072782



Program started: 2026-05-24 11:56:03

======================================================================
                      TIMING SUMMARY
======================================================================
Input Reading.......................................   0.001 s  (   0.2 %)
  Settings Parsing....................................   0.000 s  (  16.7 %)
  Coordinate Section Parsing..........................   0.000 s  (  22.8 %)
  Post-Processing Expansion...........................   0.000 s  (   0.3 %)
MLP Initialization..................................   0.119 s  (  25.7 %)
Job Dispatching.....................................   0.342 s  (  74.0 %)
  Single Point Energy Calculation.....................   0.342 s  (  99.8 %)
======================================================================
Total wall time: 0.462 s
Total CPU time: 0.729 s
======================================================================

Program ended: 2026-05-24 11:56:03
TOTAL RUN TIME: 0 days 0 hours 0 minutes 0 seconds 462 msec

The energy value represents the total electronic energy of the system at the given geometry as predicted by the specified ML potential.

Use Cases

Single point calculations are useful in a variety of scenarios:

• Benchmarking -- comparing energies from different ML models or against reference DFT/ab initio values for the same geometry.
• Energy comparisons -- evaluating relative energies of conformers, isomers, or reaction intermediates at their respective geometries.
• Post-optimization checks -- verifying the energy at an optimized geometry using a different or higher-level model than was used during optimization.
• Gradient analysis -- use verbose=1 to inspect whether a structure is close to a stationary point.
• Workflow building blocks -- SP calculations serve as the fundamental energy/force evaluation used internally by optimization, frequency, TS search, and other iterative tasks.