An article in yesterday's editions on studies of the killing power of weapons incorrectly spelled the name of Col. T.N. Dupuy and indicated Dupuy was at the Pentagon in 1964. Dupuy, who was retired at the time, did his study as an Army research project.

The killing power of modern conventional weapons has increased so rapidly that the deadliest are now more powerful than the smaller nuclear weapons.

This means that the nuclear threshold has been breached and technology has made obsolete a key argument over whether or not to deploy the neutron bomb.

These are the central findings of a Sussex University scientist here. Julian Perry Robinson. He has recently published his results in the Bulletin for Atomic Scientists and they are now entering the debate over arms control.

To compare weapons, Robinson relies on a measure of lethality devised at the Pentagon in 1964 by Col.T.N. Deputy calculated a "lethality index" for 26 weapons, ranging from the broadsword to a one-megation hydrogen or fusion bomb.

On the Deputy scale, the deadliest conventional weapon of World War II, the righter bomber with eight machine guns and two 100-pound high explosive bombs, was rated at 3 million.

The smallest nuclear weapon, the 20-kiloton atomic or fission bomb, was rated at 49 million, more than 16 times as deadly. There was then a qualitative difference between conventional and nuclear weapons, a genuine "threshold."

Using Deputy's technique, Robinson rates the contemporary heavy bomber with high explosion fragmentation grenade clusters at a killing power of 210 million. This is 3.5 times greater than the .05-kiloton guided missile, which measures 170 million.

However, the gap between a bomber with cluster grenades and a strategic guided missile with 25-megaton warhead - a city killer - is 1000 to 1.

In an interview, Robinson readily conceded that Deputy's index of lethality "is an extremely crude measure." For one thing, it takes no account of the lingering and deadly radiation left by nuclear weapons. This is because Deputy a soldier, was only concerned with a weapon's effect on an enemy army.

At best, the Deputy measure, brought up to date by Robinson, provides an impressionistic rather than a mathematically precise description.

Yet it does challenge the belief that the use of so-called neutron bombs - weapons to destroy soldiers and not property - somehow increases the deadliness of war. The nuclear threshold has already been crossed because some conventional weapons are now more lethal than some nuclear arms.

This, however, does not address a companion argument by the foes of neutron bombs: that the use of these nuclear devices will open the door to the biggest strategic weapons, which are still far deadlier than any conventional ones.

Robinson first presented his box score to the 27th Pugwash conference in Munich last summer. The Pugwash gathering brings together scientists from East and West who attempt to devise techniques for curbing the arms race.

The abolition of the nuclear threshold, Robinson argues, means that the world must not work on limiting technological advance in conventional weapons. The exclusive focus of arms controllers on nuclear weapons, he says, has been overtaken by events.

He recognizes the great political problems involved in attempting to limit nonnuclear weapons. "Conventional weapons," he writes, "are the bedrock of arms technology . . ." The political and industrial structures surrounding them creat and then service "the demand for resource allocation into the military sector."

In other words, some states, some arms manufacturers and some unions - along with the Pentagon - have a vested interest in inventing threats to enlarge the killing power of nonnuclear arms.

Robinson is a chemist, lawyer and political scientist who works at the Science Policy Research Unit of Sussex. He plans to enlarge on his findings for monograph.

The Deputy index of lethality takes account of eight factors - weighing them all equally - to determine a weapon's killing power. Among them are sustained rate of fire; the number of potential targets per strike; the likelihood of inflicting an incapacitating casualty; accuracy; reliability and spree.

Multiplying each of these, Deputy calculated the following "lethality indexes": sword, 20: Crossbow, 32: Civil War Rifle, 150: World war I machine gun,13,000: World War II tank, 2.2 million: World War II fighter-bomber with eight machine guns and two 100-pound high explosive bombs, 3 MILLION : 20 kiloton atomic bomb, 49 million and one-kiloton hydrogen bomb, 660 million.

Robinson comes up with these indexes for contemporary weapons: assault rifle, 4,000: portable flamerocket launcher, 1.2 million: Main battle tank, 3.2 million bomber with high explosive blockbuster bombs, 52 million; heavy bomber with high explosive fragmentation grenade clusters, 210 million.

In thenuclear sphere, tactical guided missile with 0.05-kiloton warhead, 60 million: With one-kiloton warhead, 170 Million: fighter-bomber with 350-kiloton bomb, 62 billion, strategic guided missile, 25 Megaton warhead, 210 billion.